When working with a production app it is critical to have separate isolated dev and production projects so as to not introduce errors in the live production project while developing new features/fixes etc.

For this use case it is not enough to have multiple Apps support as multiple apps within the same project share a single firestore database among other modules.

Below is a blog post I found that details a bit about the way this could be done for android apps. However cross platform is a must and I think an rn-firebase solution is needed.

https://firebase.googleblog.com/2016/08/organizing-your-firebase-enabled-android-app-builds.html