My music collection is still less than hundreds of GBs, so I give up doing my own streaming for now.
My setup is super simple, I just sync my Music folder by Syncthing app on all my devices.
To download on my Android phone I use NewPipe to find a song (in three-dots menu there is section specific to songs without videos) and share it to the Seal app. On computer I use yt-dlp command, but there are nice apps on Flathub too.
By this I do not need sophisticated automated system, only need to put file downloaded from YouTube, ripped from CD by abcd or pirated from torrent in Music folder and then it's synced.
This is because I found streaming apps using D-Sub or Subsonic protocols very clunky and just bearable, while custom ones like for Jellyfin are not available or the best on all platforms.