Comment by jeroenhd

Custom Windows shells go all the way back to Windows 9x. All you need to do is hide the task bar (or kill explorer.exe) and run your own replacement. Even Microsoft released a downloadable window manager of sorts with PowerZones and they added a registry key at some point so people could stop breaking their updates by replacing explorer.exe and just specify a replacement executable instead.

Custom shells might break some shitty old programs relying on Explorer running as a shell, but the Windows 11 taskbar probably killed those off already.

There are API differences between Linux and Windows of course, but nothing that Linux has that Windows doesn't. As this is based on Qt, a lot of API compatibility will probably already have been taken care of. It just requires someone to go through the effort of writing and maintaining their OS ports.