It depends on what you are looking for but mpd works well if you have the music somewhere. https://www.musicpd.org/ https://wiki.archlinux.org/title/Music_Player_Daemon

There are many client available. I think the relatively high number of clients shows you how decentralized it is.

I knew someone who had all his music on an iPod. Pretty convenient and decentralized but highly depending on iTunes, and I think SSDs are relatively cheap now, unless you save everything in flac.