Or languages that compile to JS (like TypeScript). Maybe one day we'll get languages compiling to Dart[1].

[1]. Although it'll be a pity. JS is stuck as a compilation target because it's a standard, and it's old, and even then wasm may one day take over JS. Flutter could have been a library, and one could have written in Go or Rust or Java with Flutter bindings. As it is now, I don't know if its possible.