This week, I've been working on a Docker image which ships the migration script PyQt5 to PyQt6 made by @CabiecesJ and @florent001 to automatically check @QGIS plugins against Qt6. It's now usable locally as in a CI.
I've updated the relevant wiki: https://github.com/qgis/QGIS/wiki/Plugin-migration-to-be-compatible-with-Qt5-and-Qt6
