I've always thought that Rust and React Native would be a good match. Native extensions for React Native tend to be written either in platform specific code (or C++ which just isn't nice anywhere). Rust is approachable for developers coming from JavaScript (i.e. React Native developers) and works nicely cross-platform.
In my dream world, cross-platform modules which currently bridge separate Java/Kotlin (Android) and Swift/Obj-C (iOS) functionality into a single JavaScript API would instead bridge them into a single Rust API (which could then be bridged into JavaScript), which would allow cross-platform access to Android/iOS APIs from fast native code modules as well as from JS.
"React Native apps rely on a single JavaScript thread, which can slow things down when handling complex tasks. Developers have traditionally worked around this by writing code twice – once for iOS and once for Android – or by using C++, which can be difficult to manage. Uniffi for React Native offers a better solution by enabling developers to offload heavy tasks to Rust, which is now easy to integrate with React Native."
In my dream world, cross-platform modules which currently bridge separate Java/Kotlin (Android) and Swift/Obj-C (iOS) functionality into a single JavaScript API would instead bridge them into a single Rust API (which could then be bridged into JavaScript), which would allow cross-platform access to Android/iOS APIs from fast native code modules as well as from JS.