In Android 10 we are now able to select which output we want to use for playing back audio.
Is there any documentation about how to add devices to this list (can apps perhaps register themselves to stream audio over a network etc.), or is it literally only bluetooth and the device itself?
What determines if a bluetooth device shows up? On my phone, both my bluetooth headphones and my not-very-smart smartwatch show up (despite the latter literally not having any speakers or anything), however my raspberry pi which I've configured as a bluetooth sink does not show up. If I connect to it, the phone just thinks I am playing back via "Phone speaker" (however the media volume icon changes from a music note to a music note with a bluetooth icon on it).