Nice, thanks for sharing your thoughts. Currently, I use navidrome[1], which not really is a player but more a music server, but since it supports the "subsonic" protocol, you can use native apps to connect and manage your stuff (substreamer for android / iOS is all I really need but navidrome also comes with a handy web interface). It also has support for json based smart playlists[2].
1: https://www.navidrome.org/ 2: https://github.com/navidrome/navidrome/issues/1417