I want to send in-app messages to my mobile application. Is it correct that Firebase in-app messages will work even when push notifications are switched off or not permitted? I know how to send Firebase in-app messages using Firebase Console. Can I do it from my back-end? Using API or AWS SNS?
Is it correct that Firebase in-app messages will work even when push notifications are switched off or not permitted?
Yes.
I know how to send Firebase in-app messages using Firebase Console. Can I do it from my back-end?
No.
Using API or AWS SNS?
No, there is no documented API for this. If this is something you want, you should contact Firebase support directly to make a request. Stack Overflow can't help with this.