React Native’s support for UIScene was merged only two weeks ago, and is currently in an RC. That means developers creating a new React Native app *today* won’t even have a resizable app. They also won’t be able to submit their app with Xcode 27 because iOS will crash it at launch. I don’t know about the state of affairs on Flutter. But I generally don’t think that developers using cross-platform tools tend to give much weight to what Apple wants them to do. The iPhone Duo needs apps to actually conform to its affordances, in order to deliver on the UX that its price tag implies. I suspect this will go very poorly.