Why target one platform when your project can target all major platforms (web, iOS, Android, MacOS/Windows/Linux)? Especially if you're already experienced with React and can later hire from that monstrous talent pool?
Hell, instead of casting that wider net for users, you could still only release/focus on iOS, but still have tons of work done when you're ready to move your React app to those other platforms.
Hell, instead of casting that wider net for users, you could still only release/focus on iOS, but still have tons of work done when you're ready to move your React app to those other platforms.