My suggested blurb for the Xwayland-on-demand bit:

Mutter and GNOME Shell 3.34 earned the ability to run as a pure wayland compositor, while still providing seamless compatibility with X11 by starting XWayland when required by applications. This is the culmination of much prior effort at refactoring internals and ironing out indirect X11 dependencies throughout Mutter and GNOME Shell specifically, and the GNOME session generally.

Being able to start Xwayland and other related X11 services on demand for legacy applications came out organically, and demonstrates we are no longer tied by our legacy support.

This feature is disabled by default, and can be enabled by adding 'autostart-xwayland'
to `org.gnome.mutter experimental-features`.

Thanks @carlosg, added your text above.