[Python] PyInstaller with MSIX packaging - DLL loading issues and certification requirements

When I package my Python app with PyInstaller (--onefile) and then into MSIX, I get this error on launch:

Failed to load Python DLL 'C:\Users\USER\AppData\Local\Temp_MEI123456\python311.dll'. LoadLibrary: <FormatMessageW failed.

What I've tried:

• Both --onefile and --onedir PyInstaller modes
• Including all data folders with --add-data
• Different MSIX publisher identities
• Verified all files are in the MSIX package

Environment:

• Python 3.11
• PyInstaller 5.13.0
• Windows 11
• MSIX packaging

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