@aaron.ogle I’ve now looked into firebase cloud messaging, FCM, and I cannot see why the existing mobile apps cannot register for message notification from multiple servers without needing your AWS gateway. There is also no need to expose the secret key from your own FCM account.
My understanding is that each RC web host can open a FCM account (which is free) and create their own RocketChat project, so that they obtain a SENDER_ID and API_KEY for their server/domain. Both keys can be provided to the RocketChat server application at runtime via environment variables.
Then the Android/ios apps can connect to multiple servers by requesting a SENDER_ID, when they login (possibly via a secure websocket), fetch the corresponding FCM registration token and share it with the server.
A node.js server can multicast messages to a maximum of 500 token IDs per send invocation.