Free software is, at its core, about the users having control over their own use of the software - the software isn't controlled by some owner and licensed by the users, but instead all users have equal ability to understand and use the software. If you consider communism to be political, then free software is political, because free software is communism in its purest form.

Unity would probably work under windows 11, since Windows is generally good at backwards compatibility. However, I can't confirm myself since I don't use windows or Unity. Perhaps ask if your son would consider using Godot instead of Unity in case it doesn't work (or even if it does, since Godot is the better engine for most use cases anyway IMO).