> Yes, there are many UI implementations in Windows but they are almost totally transparent to the user (no pun intended), and they can all run on the same system at once.

I mean this is a solved problem on linux using modern distributions like NixOS or even 'normal' distros with flatpak, appimage, etc. I haven't had to deal with anything like this in years.

The windows UIs are way more different than linux was. There was a time in the 90s where UIs were expected to follow platform specifics. These days, most UIs don't and they're almost kind of like the branding. Thus, this is not as big a deal as you're making it out to be. If anything, things like the gnome apps and gtk4 are more consistent than any windows app.