According to [0] there have been several releases in the last 10 years.
Including one in 2021 that added variable refresh rate and touchpad gesture support.
If you run `cage`, it will run a Wayland application in its own sandboxed window while the rest of the system runs X.
Similarly; if you run `sway` under X for example, it will start the window manager in its own window, and you can run Wayland applications inside it.
On the input side: touch gestures recognized as touch gestures, not as mouse emulation.
On both: hotplug of all input/output devices. Headless sessions and handover of sessions between console and headless, both directions. Reliable lock screen, even if popup menu is showing ;).
Impossible. I'm told if you're not running xscreensaver it is safe to assume that your screen does not lock!
Pop quiz, how many of those work on wayland?
And the last missing thing is WIP.