We built the first version of our app with RN and it turned out a mess in a while. A lot of bugs along with poor performance out of the box for a fairly large app. Many things, that native platform has, cannot be done with existing solutions for RN. For instance, large titles on iOS are not fully implemented in any of existing navigations libraries. Also there's painfully slow JSON bridge and many other small, yet annoying things. On the other hand Flutter became a really powerful and easy-to-use tool. A bit of a learning curve, of course, because of Dart, but it worth learning. Flutter offers TONS of built-in features, no JSON-bridge, AOT compilation for iOS.