Really any of them. Swift UI is the only example I can think of where a group of folks are working on making UI easy and intuitive to create and manage inside of a native language.
Why is there not an effort to make something as intuitive in C++ or GO or Rust? C++ would probably be the hardest one, sure, and there are many UI frameworks for all of these languages but none of them are as simple or intuitive as Swift UI or how React / Vue works inside of JS.
I'd love to see some more experimentation in ways of building UI in native languages. Heck, even in managed languages like C# or Java they could use the same type of treatment.
I'm sure Facebook could have written React Native in C, C++, Go, Java or Rust, but take a guess at what the adoption rate and the hype around it would have been...
If Netscape/MS browser in the 90s had shipped with an embedded, sandboxed JVM with native browser APIs, then maybe the world would be very different today, but we work with what we have don't we all?