No, they don't. I don't think Wayland ever supported exclusive fullscreen, MacOS doesn't, and Windows killed it a while back as well (in a Windows 10 update like 5-ish years ago?)
Jitter is a non-issue for things you want vsync'd (like every UI), and for games the modern solution is gsync/freesync which is significantly better than tearing.
Isn't that true for even the most basic features you expect from a windowing system? X11 may have come with everything and the kitchen sink, Wayland drops all that fun on the implementations.
GNOME does unredirect on Wayland since 2019: https://www.reddit.com/r/linux/comments/g2g99z/wayland_surfa...
> Windows killed it
They replaced it with "Fullscreen Optimisations", which is mostly the same, but more flexible as leaves detection of fullscreen exclusive windows to the window manager.
https://devblogs.microsoft.com/directx/demystifying-full-scr...
As far as I can find the update removed the option to turn this of.
Window's actual exclusive fullscreen always caused tons of issues with Alt+TAB because it was designed for a time when you couldn't fit both a game and the desktop in VRAM.
Yeah, it avoids doing the compositing part of being a compositor. It bypasses the entire pipeline.
[*] Well, there was an extension (can't recall the name right now) but not much used it and support was dropped at some point.