I’ve done this myself and the thing that ultimately blocked me from enjoying my iPod is the fact that I wasn’t able to take my music library, which is all streaming, and put it on my iPod.

It is still on my todo list to write a high quality open source scraper for Apple Music and/or Spotify

One pro tip to go further is that you can get a teeny tiny 30 pin Bluetooth adapter and listen using AirPods. It works great, and is a great use of the larger battery: https://store.kokkia.com/i10stinybluetoothipodtransmitterfor...

bitexploder

Best I have seen is a thing that converts Spotify playlists to YT ones and then just use youtube-dl. I have seen some automation around this. It is 80-90% accurate and requires a little cleanup in terms of playlist conversation, same versions of songs etc.

maybe_pablo

This (commercial) program[1] does the job for Spotify. I think what it does is just play the given playlist then it sets Spotify's audio output to a virtual audio device similar to BlackHole[2], then reads from it, encodes the audio, fetches the metadata (including album art) and sets it. There are open source[3] alternatives[4] but I haven't tested them.

[1] https://www.noteburner.com

[2] https://github.com/ExistentialAudio/BlackHole

[3] https://github.com/jwallet/spy-spotify

[4] https://github.com/richardk80/spotify-ripper