[multipolygon]

Thanks! My RFID project there is probably very over-complicated compared to a "proper" audio setup like you describe. Really all you would need is a Raspberry Pi to host a MQTT server and play a stream from Spotify (or similar). You could then use ESPHome as a simple RFID-to-MQTT reader, which would be extremely simple with ESPHome and is the kind of project that ESPHome makes beautifully and laughably simple!

[KAKAN]

My idea was even simpler tbh, I'd make a bunch of m3u files, and rename them with a SHA1 hash. Then just put the hash value in RFID tags. Yes, it's not as remotely extendable, but then again, I've like 5 or 6 offline-only playlists that I keep playing on repeat according to my mood, so I'd be fine haha

Maybe throw in album hashes or something. Extremely minimal, and everything inside the box. There won't be any Wi-Fi connections at all. Of course, this does limit some things, but eh. Maybe I'll add a WebUI for controlling volume and such, but that would be it, I guess :D