To my knowledge, X11 didn't offer a comprehensive accessibility API either - there's no Linux equivalent of stuff like MS Active Accessibility or MSUIA on Linux.
Even back then Qt, GTK and everyone else offered their own API and screen readers needed to integrate with every single one - this didn't really change under Wayland, only the sandboxing makes certain operations harder, but the accessibility story on Linux is not great, and never was.
The standard was Extended Window Manager Hints [0].
Above X11, implemented by GTK and everyone else. Right.
However... Wayland makes it impossible to implement EWMH. Which means the enrire EMWH standard needs to be tossed, and everyone needs to make something new.
You can't even get the title of a window, under Wayland. That's private to that process tree.
Wayland requires accessibility be implemented at the application level, not the window manager. And thats guaranteed to make it always broken for a majority of use cases.
Even back then Qt, GTK and everyone else offered their own API and screen readers needed to integrate with every single one - this didn't really change under Wayland, only the sandboxing makes certain operations harder, but the accessibility story on Linux is not great, and never was.