Good to know! Thanks for reporting back at each step. I'm using the pieces from this thread to document for the future.
If you use any third-party gui plugins, you may run into problems with those that rely upon PySide6. We should be able to work something out there, too. I even have a beta stand-alone Python AppImage that can be used as the Python interpreter for Sigil plugins. It has all of Sigil's recommended extra modules (including PySide6) already packaged. It's testing well.
Check here if interested:
https://github.com/dougmassay/appima...eleases/latest