Myfriend is a social networking app that supports Android Studio, Firebase & Admob.
Demo: https://codecanyon.net/item/myfriend-friends-posts-groups-chat-follow-social-networking-app-android-studio-firebase-admob/27901283
With the friends extension you can increase user interaction on your site by allowing users to become friends by sending & accepting / rejecting friend requests
Demo: https://ultimatemember.com/extensions/friends/