I then use the virtual cam plugin to make that my webcam feed. This works great, but what I'd also love to do is take the audio from the phone mic as a browser input and use it as a virtual microphone. I've only been successful by using a VBCable pipe and setting the monitoring device, but what that ends up doing is also playing all of the sound OBS is capturing from my phone into my headphones too, so I get my own voice. If I mute OBS, the monitoring doesn't work, and so I get no audio.
If I capture the audio completely outside OBS with another mic, everything's out-of-sync and I don't have portable audio.
This is so close to a seamless way to turn any phone into a portable webcam with mic, but I haven't figured out that last little piece of the puzzle. However, I wanted to 1) shout out OBS for being such an incredible piece of software, and 2) shout out obs.ninja for what it does. Seriously impressive.
[1]: https://obs.ninja/