This is the extension that I created to integrate Firebase analytics into my game. It provides quite limited functionality - stuff I only needed for my game. But you can to extend it by your own.
Platforms supported: Android, iOS
See documentation here : https://docs.google.com/document/d/1Y9E6uPagsNUadgggggCBcDFSPEjjSwks6tv6PHz2vDI/edit?usp=sharing
With any questions write to firstname.lastname@example.org