diff --git a/.github/workflows/app-build-verify.yml b/.github/workflows/app-build-verify.yml
index b2e7301..3dcb5ed 100644
--- a/.github/workflows/app-build-verify.yml
+++ b/.github/workflows/app-build-verify.yml
@@ -10,7 +10,7 @@ on:
     inputs:
       python-version:
         description: "Python version to use; defaults to latest Python release."
-        default: "3.X"
+        default: "3.x"
         type: string
       runner-os:
         description: "The OS to use to build the App; must be a fully qualified GitHub runner OS, e.g. ubuntu-latest."
@@ -82,9 +82,6 @@ jobs:
         fi
         echo "cache-key=$(date +%Y-%m)|${CACHE_KEY}" | tee -a ${GITHUB_OUTPUT}
 
-        SYSTEM_PYTHON_VER=$(python3 -c 'import sys; print(f"{sys.version_info.major}.{sys.version_info.minor}")')
-        echo "system-python-version=${SYSTEM_PYTHON_VER}" | tee -a ${GITHUB_OUTPUT}
-
     - name: Checkout ${{ inputs.repository }}
       uses: actions/checkout@v4.2.1
       with:
@@ -111,11 +108,14 @@ jobs:
         path: ${{ steps.config.outputs.briefcase-data-dir }}
 
     - name: Set Up Python
-      # Linux System apps requires python is System Python to run the app
-      if: ${{ !startsWith(inputs.runner-os, 'ubuntu') || !startsWith(inputs.python-version, steps.config.outputs.system-python-version) }}
+      # On Linux, accept "system" as a proxy for "don't install Python"; this will
+      # fall back to the system-provided Python package. Providing "system" as a value
+      # on macOS or Windows will cause an error.
+      if: ${{ !startsWith(inputs.runner-os, 'ubuntu') || inputs.python-version != 'system' }}
       uses: actions/setup-python@v5.2.0
       with:
-        python-version: ${{ inputs.python-version }}
+        python-version: ${{ inputs.python-version || '3.x' }}
+        allow-prereleases: true
         cache: pip
         cache-dependency-path: |
           **/setup.cfg
@@ -222,7 +222,7 @@ jobs:
     - name: Build Linux System Project (Ubuntu, local)
       if: >
         startsWith(inputs.runner-os, 'ubuntu')
-        && startsWith(inputs.python-version, steps.config.outputs.system-python-version)
+        && inputs.python-version == 'system'
         && contains(fromJSON('["", "Linux"]'), inputs.target-platform)
         && contains(fromJSON('["", "system"]'), inputs.target-format)
       working-directory: ${{ steps.create.outputs.project-path }}
diff --git a/.github/workflows/app-create-verify.yml b/.github/workflows/app-create-verify.yml
index 9496f59..cdad1e8 100644
--- a/.github/workflows/app-create-verify.yml
+++ b/.github/workflows/app-create-verify.yml
@@ -9,7 +9,7 @@ on:
     inputs:
       python-version:
         description: "Python version to use; defaults to latest Python release."
-        default: "3.X"
+        default: "3.x"
         type: string
       runner-os:
         description: "The OS to use to build the App; must be a fully qualified GitHub runner OS, e.g. ubuntu-latest."
@@ -47,6 +47,11 @@ jobs:
     runs-on: ${{ inputs.runner-os }}
     timeout-minutes: 30
     steps:
+    - name: Workflow Configuration
+      id: config
+      run: |
+        SYSTEM_PYTHON_VER=$(python3 -c 'import sys; print(f"{sys.version_info.major}.{sys.version_info.minor}")')
+        echo "system-python-version=${SYSTEM_PYTHON_VER}" | tee -a ${GITHUB_OUTPUT}
 
     - name: Checkout ${{ inputs.repository }}
       uses: actions/checkout@v4.2.1
@@ -68,10 +73,15 @@ jobs:
         path: briefcase-template
 
     - name: Set up Python
+      # On Linux, accept a value of "system", which will install a version of
+      # Python matching the system version. We can't use the actual system
+      # install because we need to install dependencies, which would either
+      # require the use of sudo, or extra workarounds for user-space packages.
       uses: actions/setup-python@v5.2.0
       with:
-        python-version: ${{ inputs.python-version }}
+        python-version: ${{ startsWith(inputs.runner-os, 'ubuntu') && inputs.python-version == 'system' && steps.config.outputs.system-python-version || inputs.python-version || '3.x' }}
         cache: pip
+        allow-prereleases: true
         cache-dependency-path: |
           **/setup.cfg
           **/pyproject.toml
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 470d932..f89dcf7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -110,7 +110,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5.2.0
       with:
-        python-version: 3.X
+        python-version: "3.x"
         cache: pip
         cache-dependency-path: |
           **/setup.cfg
@@ -261,7 +261,7 @@ jobs:
     needs: [ pre-commit, test-package-python ]
     uses: ./.github/workflows/app-create-verify.yml
     with:
-      python-version: "3.10"  # must match system python for ubuntu version
+      python-version: ${{ matrix.python-version }} # Falls back to 3.x if undefined
       repository: beeware/briefcase
       runner-os: ${{ matrix.runner-os }}
       framework: ${{ matrix.framework }}
@@ -270,13 +270,17 @@ jobs:
       matrix:
         framework: [ toga, pyside6 ]
         runner-os: [ macos-latest, windows-latest, ubuntu-22.04 ]
+        includes:
+          # Ubuntu apps need to run on the system Python
+          - runner-os: ubuntu-22.04
+            python-version: "system"
 
   test-verify-apps-briefcase:
     name: Verify Briefcase
     needs: [ pre-commit, test-package-python ]
     uses: ./.github/workflows/app-build-verify.yml
     with:
-      python-version: "3.10"  # must match system python for ubuntu version
+      python-version: ${{ matrix.python-version }} # Falls back to 3.x if undefined
       repository: beeware/briefcase
       runner-os: ${{ matrix.runner-os }}
       framework: ${{ matrix.framework }}
@@ -285,13 +289,17 @@ jobs:
       matrix:
         framework: [ toga ]
         runner-os: [ macos-latest, windows-latest, ubuntu-22.04 ]
+        includes:
+          # Ubuntu apps need to run on the system Python
+          - runner-os: ubuntu-22.04
+            python-version: "system"
 
   test-verify-apps-briefcase-template:
     name: Verify Briefcase Template
     needs: pre-commit
     uses: ./.github/workflows/app-build-verify.yml
     with:
-      python-version: "3.11"
+      python-version: "3.11"  # Explicitly test the python-version override
       repository: beeware/briefcase-template
       runner-os: ${{ matrix.runner-os }}
       framework: ${{ matrix.framework }}
@@ -306,7 +314,6 @@ jobs:
     needs: pre-commit
     uses: ./.github/workflows/app-build-verify.yml
     with:
-      python-version: "3.11"
       repository: beeware/briefcase-android-gradle-template
       runner-os: ${{ matrix.runner-os }}
       target-platform: android
@@ -323,7 +330,6 @@ jobs:
     needs: pre-commit
     uses: ./.github/workflows/app-build-verify.yml
     with:
-      python-version: "3.11"
       repository: beeware/briefcase-iOS-xcode-template
       runner-os: macos-latest
       target-platform: iOS
@@ -339,7 +345,8 @@ jobs:
     needs: pre-commit
     uses: ./.github/workflows/app-build-verify.yml
     with:
-      python-version: "3.10"  # must match system python for ubuntu version
+      # Ubuntu apps need to run on the system Python
+      python-version: "system"
       repository: beeware/briefcase-linux-system-template
       runner-os: ubuntu-22.04
       target-platform: linux
@@ -355,7 +362,6 @@ jobs:
     needs: pre-commit
     uses: ./.github/workflows/app-build-verify.yml
     with:
-      python-version: "3.11"
       repository: beeware/briefcase-linux-appimage-template
       runner-os: ubuntu-latest
       target-platform: linux
@@ -372,7 +378,6 @@ jobs:
     needs: pre-commit
     uses: ./.github/workflows/app-build-verify.yml
     with:
-      python-version: "3.11"
       repository: beeware/briefcase-linux-flatpak-template
       runner-os: ubuntu-latest
       target-platform: linux
@@ -388,7 +393,6 @@ jobs:
     needs: pre-commit
     uses: ./.github/workflows/app-build-verify.yml
     with:
-      python-version: "3.11"
       repository: beeware/briefcase-macos-${{ matrix.format }}-template
       runner-os: macos-latest
       target-platform: macOS
@@ -405,7 +409,6 @@ jobs:
     needs: pre-commit
     uses: ./.github/workflows/app-build-verify.yml
     with:
-      python-version: "3.11"
       repository: beeware/briefcase-web-static-template
       runner-os: ubuntu-latest
       target-platform: web
@@ -421,7 +424,6 @@ jobs:
     needs: pre-commit
     uses: ./.github/workflows/app-build-verify.yml
     with:
-      python-version: "3.11"
       repository: beeware/briefcase-windows-${{ matrix.format }}-template
       runner-os: windows-latest
       target-platform: windows
diff --git a/.github/workflows/dep-version-bump.yml b/.github/workflows/dep-version-bump.yml
index 4721932..42487dc 100644
--- a/.github/workflows/dep-version-bump.yml
+++ b/.github/workflows/dep-version-bump.yml
@@ -72,7 +72,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5.2.0
         with:
-          python-version: 3.X
+          python-version: "3.x"
 
       - name: Install Dependencies
         run: |
diff --git a/.github/workflows/pre-commit-run.yml b/.github/workflows/pre-commit-run.yml
index b6f2543..99d27b2 100644
--- a/.github/workflows/pre-commit-run.yml
+++ b/.github/workflows/pre-commit-run.yml
@@ -9,7 +9,7 @@ on:
     inputs:
       python-version:
         description: "Python version to use; defaults to latest Python release."
-        default: "3.X"
+        default: "3.x"
         type: string
       repository:
         description: "GitHub repository to checkout; defaults to repo running this workflow."
@@ -44,6 +44,7 @@ jobs:
       uses: actions/setup-python@v5.2.0
       with:
         python-version: ${{ inputs.python-version }}
+        allow-prereleases: true
         cache: pip
         cache-dependency-path: |
           **/setup.cfg
diff --git a/.github/workflows/pre-commit-update.yml b/.github/workflows/pre-commit-update.yml
index 4d67921..ddd4d96 100644
--- a/.github/workflows/pre-commit-update.yml
+++ b/.github/workflows/pre-commit-update.yml
@@ -75,7 +75,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5.2.0
         with:
-          python-version: 3.X
+          python-version: "3.x"
           cache: pip
           cache-dependency-path: |
             **/setup.cfg
diff --git a/.github/workflows/towncrier-run.yml b/.github/workflows/towncrier-run.yml
index b51051e..dd6021f 100644
--- a/.github/workflows/towncrier-run.yml
+++ b/.github/workflows/towncrier-run.yml
@@ -9,7 +9,7 @@ on:
     inputs:
       python-version:
         description: "Python version to use; defaults to latest Python release."
-        default: "3.X"
+        default: "3.x"
         type: string
       repository:
         description: "GitHub repository to checkout; defaults to repo running this workflow."
@@ -55,6 +55,7 @@ jobs:
       uses: actions/setup-python@v5.2.0
       with:
         python-version: ${{ inputs.python-version }}
+        allow-prereleases: true
         cache: pip
         cache-dependency-path: |
           **/setup.cfg