Example to integrate firestore in Xamarin.Forms Andriod/IOS?

So, im trying to implement this libraries inside my project:
Firestore Android:
https://www.nuget.org/packages/Xamarin.Firebase.Firestore/60.1142.0-beta2

Firestore IOS:
https://www.nuget.org/packages/Xamarin.Firebase.iOS.CloudFirestore/

And I've only found 1 example of how to use them both:
https://github.com/yamachu/Sample-Firebase-Cloud-Firestore-Xamarin.Forms

Since I'm having problems when adding/updating in the mapping of .NET objects to Java/NSObject respectively. Does anyone know a library that provides an example of that?
Thanks!