Would it be a) possible and b) a good idea when you open the app / are on the home page and hit the play button on the headset to resume the latest album with a resume marker?
Not really for both 
See the other discussions about saving the player state on kill.
I guess at some point for the users who are in simpler configuration I may add an option to keep the player state despite the possible side effects.
Yeah, I get it, that album might not even be available at that moment. It is just my “trained behaviour” from long usage of local music players to start the app and almost immediately lock the screen again because I can resume playback wherr I leftboff last time with the headset. But Symfonium covers also different use cases.