I’m not 100% sure we both are talking about the same things but I’m going to assume you mean playing songs on Spotify and then having your phones lockscreen display that song.
The answer to that is UI APIs, your phone likely exposed APIs to developers who make apps for your phone. They can use these system APIs to tell your phone’s music display UI thing what song you are playing and what the buttons (next, prev, stop/play should do)
These APIs are client side but I wouldn’t be surprised if they phoned home in some way.
An example of this could be that the internal UI API may phone home to tell Google that a client is choosing Spotify as their music player.
That being said I don’t know if this is practical or likely. It is possible and doable though.
Then how does Google figure out what music is playing in the background to display it on the lock screen?
I’m very happy to have GrapheneOS on my phone now.
I’m not 100% sure we both are talking about the same things but I’m going to assume you mean playing songs on Spotify and then having your phones lockscreen display that song.
The answer to that is UI APIs, your phone likely exposed APIs to developers who make apps for your phone. They can use these system APIs to tell your phone’s music display UI thing what song you are playing and what the buttons (next, prev, stop/play should do)
These APIs are client side but I wouldn’t be surprised if they phoned home in some way.
An example of this could be that the internal UI API may phone home to tell Google that a client is choosing Spotify as their music player.
That being said I don’t know if this is practical or likely. It is possible and doable though.