I'd love to hear about any places to look for this. I sometimes want to download some favourite songs, just in case they go down on any music services or youtube.

I feel there is room for improvement over the soulseek network, though that's about the best there is right now. It doesn't take advantage of downloading from multiple peers (like torrents), quality is good in practice but hard to be sure until you listen, and is missing rare / non-western music.

While streaming apps offer a decent value, I don't like the level of lock in. I have music from CDs and other sources that are a first class part of my library, and using only a streaming app would make them harder to access.

I really like Apple Music. Actually supports lossless, unlike Spotify, and it just feels much more music focused. Spotify has become too bloated, and I view it more as a "sound" app than a music app.

finding FLAC or WAV with active seeders feels like striking gold

Not if you're on the right tracker(s)...really should try and get into RED and/or Orpheus.

I personally download YouTube videos, convert them to MP3 and then add metadata to them.

I just download all of my music with a Telegram bot tbh