This is a really cool project by @ariadne
https://github.com/kaniini/wayback
It's a Wayland compositor, emulating a full X11 server via xwayland. It's using the wlroots library.
This makes forks like Xlibre obsolete, as everyone can just use Wayland, and run X11 desktops in this compatibility layer.
Her motivation is to reduce the X11 maintenance burden in Linux distros.
Still a lot of bugs for now (afaik Ariadne only started on it *days ago*) but I see this being used in every distro, in the future.