yt-dlp for downloading, https://picard.musicbrainz.org for tagging it, and https://flathub.org/en/apps/org.gnome.Lollypop for a music player

For mobile:

newpipe for downloading, and https://play.google.com/store/apps/details?id=org.fossify.musicplayer as the player

Then I use Syncthing to sync all the music across my devices. So far its been nice, and I have the mp3 files so it always works offline unlike spottily