I've run into this. I would like to use my Android phone as speaker and microphone for my laptop, so I can walk around without leaving my call. For some reason this is impossible, Bluetooth supports it of course, and so does Pulse Audio on my laptop, but an Android phone will only act as the host not the speaker/mic.
I found SnapCast which lets me send audio from laptop to phone (with huge latency) but not the other way (phone mic to laptop).
I found SnapCast which lets me send audio from laptop to phone (with huge latency) but not the other way (phone mic to laptop).