There's some reason to your proposition. Directly integrating/"embracing" foreign toolkits/web engines is the last thing Apple would ever do, but exposing more of the underlying machinery to allow third parties to integrate better - yeah, sounds good.

On the topic of Rust GUIs on Mac, this was recently in the news:

https://github.com/emilk/egui/commit/e1f348e4b24c2fa83d25c6a...