Ace! _SL/S

FMHY has some good ones for high quality music. Organizing your Library will also be real easy with Musicbrainz Picard.

As for mass downloading there should be some Spotify downloaders out there. Every other way will proly not be able to get 100% of your library. Just make sure to use a trusted one, because you’ll most likely have login with your account to access your saved stuff & playlists.

Personally I download from Tidal for HiFi (yt-dlp + hifi-tui) and Youtube Music (yt-dlp) for everything else.

JShelter and uBO medium mode to the rescue. Pair that with Librewolf and you’re pretty secure against fingerprinting.