I am working with expo and had to use "@react-native-google-signin/google-signin package that was not directly supported by the expo so I had to make an development build for expo (Containing android folder).
So, my question is in production do we really need this or not? Or is it only required for the development process?
The Android / iOS folders are created for use cases like yours, when something deeper has to be changed manually. It gives the developer more breathing space & freedom on what he or she can do with it.
As far as my understanding goes, this is only needed for the development part. I do not see how one would use these folders in production, aside from building an APK or AAB file.
If you are interested, be sure to look into the documentation of Expo