I'm developing an app and am trying to work out how I can notify a specific user when a different user performs a specific action. I'm trying to avoid setting up my own backend server, as I believe that what I want to do can be accomplished by OneSignal/Firebase.
I haven't tried it yet, but I figure with each user I could get their own OneSignal player_id (which is basically the OneSignal device_id), upload that to my firebase database, then when I want to send a push notification I simply pull the user's player_id from firebase and then use it to create a notification with OneSignals send to specific device, where using player_ids does not require the API Auth Key.
Though after looking through the documentation I'm not sure how a user can find (so they can then upload to firebase) their player_id, so if anyone could point me in that direction it would be appreciated.
Reading through other questions, it seems like this would work. I just wanted to see if there were any like potential issues with this method or if there were any safer or easier ways to go about it.