The 47.0 Release Notes (Meta Quest release notes | Meta Store) mentioned a new experimental feature they called "Background Audio Playback". I've been looking forward to a feature like this and I am very excited to see it being worked on.
I'm posting here in the Unreal VR forum because what I REALLY want to see next is for UE4 in the Oculus branch to enable music visualizations from the audio data being streamed. It would enable an entire genre of music visualization apps that can be powered be all of the streaming audio sources that people can play in the background.
I would personally use this in my project so that the user can listen to their music how they want to while playing my game and still have my game's visuals react to the music of your choice.
If you think this is important feature that you'd like for your project, consider replying to show your support. Thanks!