Speaking from the sidelines: the currently active emacs-devel community has
a dearth of people with the right combination of time, access, and interest
to guide big changes to macOS support. If you are interested in working on
such an idea, I'll suggest just pick up the effort and push it forward
yourself, then share it with emacs via the bug-tracker (for better
centralized tracking). If you get a patch that seems to work but needs
broader testing, posting to emacs-devel can be effective, and if it's not,
we/it can help spread the word. Keep in mind that code included in GNU
Emacs will eventually need copyright assignment for non-trivial
contributions.

It's also theoretically possible to get help from the community that uses
the other widely available macOS port (search for "carbon port versus cocoa
port" if you want more history here), but, last I checked (admittedly,
quite a while back) the mac port used some significantly different internal
machinery around select that _I would guess_ has a big impact in this area,
and is effectively not directly compatible -- but might still have valuable
insights & experience to share.

If you need a *place* to work on this project, ask again here or in the
big-tracker, and probably something can be worked out.

I hope that helps! (I stopped using macOS myself several years ago, so I
can't offer more direct assistance).
~Chad