Okay I got a genius/exceptionally stupid idea.
Some of you may know Xi. If not, it's an, in development, text editor backend, written in Rust.
It does all the heavy lifting and communicates changes with the Frontend over an rpc-api, typically on stdin/stdout.

Now, why don't we do this, but for other kinds of applications, that have been reinvented a million times, because a feature is missing or the ui has been shit.
Cross-Platform backends for file-managers, web browsers, password managers, media players,...