I'm the main developer of the AccessKit [1] project mentioned in this post. AMA. To preemptively answer one expected question, I know the project has been inactive for a while; I'm back to work on it in earnest starting this month.
This is a really interesting project. Accessibility support is near and dear to my heart.
The readme mentions a macOS adapter prototype, but I don't see that directory. Does it exist in a different branch? I'd love to check it out – I'm pretty experienced with the Mac's AX implementation, but have basically no experience with AX on Windows...
Oh wow, the readme is even more out of date than I realized. I yanked the Mac adapter prototype from the main branch last year. You can find it if you dig through history. I'll bring it back and continue working on it later this year; it's already on my schedule of work to do this year.
[1]: https://github.com/AccessKit/accesskit