OpenFl isn’t a suitable replacement for React Native, or vice versa. The question is what you really want.
If it is a UI framework that uses native components, React Native is your best bet, although you could also try NativeScript, using dts2hx to generate the externs.
If I am not wrong HaxeUI also has a native backend for Android, but nothing for iOS.
If however you don’t need native components, there are many choices available to you, one of which is OpenFl. And if you want component libraries building on top, you can either use HaxeUI or FeathersUI.
As far as I know, the existing react externs for Haxe work just fine. You may find that some of the newer RN APIs aren’t yet part of the externs, but that is trivially fixed. Beyond that, if you need hooks, you may have to reach for this: Haxe-react, functional components and hooks
Either way, I think you should first define what you want to build and how Haxe fits in there, if at all (for RN TypeScript may simply be a better choice, depending on what you’re building).