Sure but the pixels painted to the screen and the gestures handled by the application code are all the platform’s native UI framework. Knowledge of the underlyi

Sure but the pixels painted to the screen and the gestures handled by the application code are all the platform’s native UI framework. Knowledge of the underlying platform UI framework is transferable. In React Native if something is slow or you want to use a recently-released native platform feature you can write a native component. That’s possible with Flutter too, but if you mix Flutter & native views, there’s a bunch of performance issues due to texture copies and thread synchronization.