I don't understand. You can do accessibility with GPUI today. I linked a repo that shows how.

Yes, and this is good progress (my comment downthread was before I just looked). According to it it uses accesskit, which is quite good already but still in development so accessibility would not be as good as using UIA directly. I am hopeful though that accesskit (which is also used in Godot) will keep getting better and these gaps can be closed.