Firebase Rewards App (iOS & Android)

Rewards type app that will receive input from a feed, send notifications to user groups and enable sharing of relevant/selected input from feed to be shared to social networks with one button click. Users will receive points for sharing and there should be a stack ranking system.

Ideally, I'm looking to create in AWS Amplify or GCP Firebase for ease of management but open to some suggestion here. IAM and possible SSO also a plus.