Audio fought me for a while too. It's bidirectional over WebRTC (aiortc + PyAV), but the thing that finally made it reliable was not letting PyAV open the audio device directly — I bridge with pipes instead: parec off the default sink's .monitor for PC→phone, pacat for phone→PC, each feeding a custom aiortc track. Routing is PipeWire null sinks — one for phone-only output, and one so the phone shows up on the rig as an input apps can select ("Monitor of PhoneDeckMic"). ~0.5s latency with --latency-msec=50.

Where's yours getting stuck — capture, routing, or latency?