YT Music - An unofficial Mac app for YouTube Music
Plexamp - A small music player with a number of unique features
Deezer iMessage app - Share your music on iMessage with Deezer!
Vinyls - Vinyls is a music player that lets you listen to your music without any complicated setup.
SoundCloud Desktop - Use your media-keys ⏮⏯⏭ with SoundCloud
Poolside FM for iPhone - A pool party in your pocket