Edit: Solved, OVRManager is returning the right thing, after all. Unfortunately I cannot seem to delete this post.
Any pointers on how to get the Oculus audio device guid? It used to be the case that OVRManager.audioOutId would work, but in unity 2019.3, this doesn't seem to work. In addition, it would be nice to get this from the XR api itself, as the user can often select how they want audio to be routed in their headset config (Oculus settings, for example).
I'm using the latest (as of this post) Oculus XR package, in Unity 2019.3.0f3. We are using FMOD, which needs to be specifically targeted at an audio out.