Isn't screen reader support implemented using AT-SPI over D-Bus? So I would expect it to be independent of the window system.

On https://www.freedesktop.org/wiki/Accessibility/AT-SPI2/ it even says:

> Wayland

> Works just the same :D

Apart from that while it's true that the compositor has to do everything, some of the interfaces seem to be shared (standardized? I don't know enough about Wayland development tbh) across different compositors: https://wayland.app/protocols/