Ideally they could make each of these separate apps. There's no technical reason why multiple apps couldn't be published by Spotify that all use the same IP.
Gmail, Drive, and Calendar all probably share a decent amount of backend data despite them all sharing some backend data as part of the G Suite, and the main Facebook app has almost a superset of the data in Messenger app (the only thing I can think of that might be missing is the "stories" stuff in Messenger, but I also don''t really know anyone who uses that). While Spotify doesn't have anti-trust concerns like Facebook and Google (at least right now), I'm a bit skeptical that there's any worries about having a combined G Suite app or merging Messenger back into Facebook proper being that much of a monopoly concern given how entwined they already are in the browser.