You could check out uYouPlus then, it doesn’t require jailbreaking or anything but instead works through “sideloading”. I’ve used it for years and it’s honestlygreat:
There was actually a project on github that claimed to allow downloading of Spotify straight from the source with drm bypassing called XSpotify but it was taken down by spotify before i got to try it:
https://github.com/meik97/XSpotify
It’s Tutanota, an email service