So our end goals are kind of the opposite. I wanted a setup that I can plug in once and not fiddle with ever which is why I wanted everything wired all the way.

So our end goals are kind of the opposite. I wanted a setup that I can plug in once and not fiddle with ever which is why I wanted everything wired all the way. My hardware investigation also occurred because I noticed that scrcpy fails to display banking/protected apps while HDMI works just fine. There should be two ways to get audio out of the phone, either via HDMI or via the cheap USB C to 3.5mm adapters. (HDMI audio splitters also exist if you need them for some reason) To get audio into the phone, the 3.5mm adapter should be able to handle that since they can handle headsets with microphones via a 3.5mm TRRS jack. I have not tried this setup out yet but it should work in theory.