I went down the rabbit hole of portable media players, even going so far as to write software to sync my Plex music library with an iPod. Unfortunately, shortly after that Spotify launched for Teslas in the US, so I switched to that full-time. I do still wish there was a small wifi and bluetooth enabled dedicated Spotify player in the vein of the square iPod nano. Ideally something that connected to my phone when available, and fell back to on-board storage when a data connection wasn't available.