They've had feature parity forever. Every app ever released hasn't been updated yet, however.
For example, you can't fetch the mouse position, you can't fire mouse events, you can't get the window z-index. These are all pretty vital for accessibility.
Whilst there are efforts to get around this terrible-ness, you can expect most accessibility tools to segfault or misbehave.
To replace X11, then, we would need something more than Wayland: a design (as a spec or as a concrete component) for how all these parts that were left out are supposed to work.
Maybe. But GNOME have found it difficult [0] [1], and the most basic of mouse control required a truly massive patch to KDE [2]. Everyone else just shrugs and says to use XWayland. Meaning there is no consistency on how to make basic accessibility work.
It isn't clear to me why reporting the mouse's location belongs in the compositor. You may not be rendering to a screen at all.
The end result being... Accessibility under Wayland is crap. Accessibility under X11 mostly works.
[0] https://gitlab.gnome.org/GNOME/mutter/-/issues/9
I'm presuming what you actually mean is that the specific features you use in insert environment on non Nvidia hardware work well enough.
Nobody wants to decide their interface based on a combination of gpu driver, apps, features are fully functional.
The actual question at hand is how many of the now more fragmented set of platform are feature complete and to what degree. Comparing apples to oranges is a waste of your time and my time.