Android Auto hates bikers.

Headunit: Harley-Davidson Boombox GTS Phone: Pixel 4xl

I need to find a solution to run Android Auto on my bikes infotainment system but direct the audio through Bluetooth to my Cardo Packtalk Bold headset in my helmet. It is driving me nuts and the only hope is appears I have is to find a way to get the phone to bypass it's USB audio protocol and connect via Bluetooth for audio only. And before you ask, yes I have researched extensively before asking. No luck so far.

Any suggestions?