This is the same as this question from 2016 (where the answer was basically: 'No'), but Android Auto since 2019 works very differently than it did 2016, so i think it is ok to ask again:
Android Auto basically gives you the ability to project app content to a car's head unit, and work with the input the user generates there. The DHU (Desktop Head Unit) is an emulator that lets a desktop computer emulate the behavior of a real head unit (for instance translating the workings of a physical dial to keyboard shortcuts, getting fake audio input from .wav files, etc) - The material that i read always assumes that you plug a phone with your app into the computer running the DHU. I would like to have it all on one computer - is it possible to connect a virtualized phone, running the app under test on the same computer as the DHU?