SixtyFPS (https://sixtyfps.io/) is in progress for Rust, but it is still early days. It also does not technically use a native toolkit (it uses Qt), but I believe that might be on roadmap. For traditional GUI apps, I think the lack of a table or tree widget is the most limiting for the time being. They have stated they intend to remedy that.

I should also add that it is GPL - with all that implies. They also have commercial licenses.