The USB drive solution solves only one part of the problem. You assume all of my music in iTunes/Apple Music. I only listen to music in that app...because the c

The USB drive solution solves only one part of the problem. You assume all of my music in iTunes/Apple Music. I only listen to music in that app...because the car plays "Aaj Ki Raat" every time I plug in my iPhone. I usually listen to podcasts or Amazon Music. A standard protocol would be great, if one exists. Treating the external device as a USB drive closes the door on other apps/functionality.