> but worst case I'll run a Wayland compositor on my X11 server for that
This is actually surprisingly easy, too. My first experiments ran a wayland app in cage ( https://github.com/cage-kiosk/cage ), but in order to better handle multiple windows I switched to sway with a lightly tweaked config, and other than some input weirdness (I think it struggles with modifiers held while switching focus) it works pretty well.