I'm not sure if it's possible which why I thought I'd ask you lot.

Does anyone know if there's a way to add Spotify playlists as a custom station to the new BoomBoxes in rust? If not natively, is it even possible as a mod? I do know that Spotify offers an API to pull playlists and audio, but not sure if that can be used in this case.

Not sure for Spotify but you can do like me and host real radio station. Install AzuraCast and run online radio in few clicks... Then download all MP3 files of the songs and upload them from AzuraCast control panel. Then load playlists with the songs that will play at different playtimes or everything at once in huge playlist and then add your MP3 stream direct link into Boombox. Idk how and where you host the server but I am on VPS so host support were happy to assist me and setup this for me because I already pay for this VPS anyways and it's not limited only for Rust Servers.

Ya mean like

Wow is this coming as release somewhere? Damn looks epic. By default we got scammed when DLC was released cuz Facepunch lied that this is exploitable and for security reasons they removed it for players but I know they can fix it if they want, they just do not want to do it for other sh*t reasons. OK, admins can still use the boombox command but after we add 4 radios 5th one does not appear and removes the previous 4 also order is sh*t and custom radios appear at the end of the list. So I can't add a lot of songs for the players separately and used to host own radio as hotfix but this plugin preview looks promising and easy for regular player to use.