SSH into a machine and open a GUI tool. I'd love to watch you do that and enjoy 2 FPS via X11-via-ssh.
You run it on some headless machine, and point your browser at the HTTP server it creates to see the full GUI. It uses Yjs to make that connection as efficent as possible, and it works great.
The desktop app is literally doing the same thing internally - it runs a headless server process and serves the GUI to its own window. But you can stretch that over a network and it's the same experience.
I can even connect to it via a TURN server, from my phone on a cell signal, and although it's not as snappy as running locally, it works pretty well.