I would like to find a way to make two android devices communicate in background, with a service starting at device startup, but communication should be P2P.
My idea is to be able to retrieve some data sent from another device, to make some changes on phone, as the wallpaper, some toasts, etc.
How could you do such a thing on android ?
I've try too look on the internet, abd found WebRTC, as well as Firestore.
Is that a good way to go ? As this is a personnal app for bow, I would like to be able to develop it without having to pay, and then if needed scale it up.