As a "batteries included" framework Qt is undoubtably amazing but I used it on a project recently and it struck me as dated compared to Flutter or React Native. Maybe I'm doing it wrong but I had to write a lot of boilerplate C++ even when using QML. The layout engine feels byzantine. The state management is mostly manual. Flutter is a lot more consistent, reactive, and all done in one way (Dart) and it supports hot reload natively. It was a more pleasant experience overall.
Qt has been going strong for 2+ decades and you can bet will do so for at least that many more. Flutter is by Google and it exists when I started writing this comment but we can't say for sure it will when I'm done writing it
And React has that "web development" ecosystem taint... I'd definitely lean towards Flutter in this case. It's neat, tidy and a contained ecosystem. It may not be fully perfect, but for cross platform UI's I think it's the way to go.
My only question is - say if one uses Rust, is flutter_rust_bridge the way to go?