[mjul]

Have a look at remacs (an experimental Rust port of emacs, now discontinued) [1] and its successor, emacs-ng (also in Rust) [2]

I haven’t followed closely, but I am sure there are som valuable lessons learned there that would answer your question.

[1] https://github.com/remacs/remacs

[2] https://emacs-ng.github.io/emacs-ng/