I'm quite fresh in the raspberry and OpenAuto world, and I'm wondering is it possible to have separate audio outputs - using integrated and external sound cards for audio output for different sources?
What do I mean? In cars like Volvo, there are separate speaker only for a driver for phone calls, and rest of audio (music, videos, etc) are played by the main sound unit.
I believe there are settings in OAP that let the sound pass though but allows for control of the device. Thus, you would connect the phone's hfp to the car's bluetooth signal for HFP but control it through OAP. Bluewave or some other more experienced user will hopefully chime in to elaborate further.