#Android:

New Material 3 YT Music Clients:

• ViMusic
• InnerTune
• Harmony-Music
• SpMp
• YouTune
• MellowMusic (New) [uses Piped API]
• SimpMusic (New) [Official YT Music Style]
• Gramophone (New) [Web-Streaming coming soon]
• Symphonica (Discontinued)

Flutter YT Music Clients

• Gyawun
• Musify
• Blackhole

Universal Clients:

• Spotube

Not really open source:

• Soundbound

#IOS:

• Blackhole
• YTMusicUltimate

#Windows:

• YTMDesktop
• Spotube

#Linux:

• YTMDesktop
• AudioTube
• Olivia
• Muzika
• Monophony
• Spotube

#Mac OS:

• YTMDesktop
• Spotube

Google Sign-In support: SpMp, YTMDesktop, Muzika, YTMusicUltimate, InnerTune

Spotify Login support: Spottube

Credits for helping with the list to u/KitkatBakeman on Reddit