Indeed, this approach worked for me too on my brand new FP6 e/os I absolutely did not dare to root with Magisk! Basically I just updated Android Auto via App Lounge, activated “Unknown sources” in Android Auto developer settings“, downloaded and installed the three stubs as described in @SalmonSnake’s post you referenced. Allowed some notification settings and Bám! Ah, yes, and needed to disconnect Proton VPN, at least it was requested at some point. Car was happy 
Did not really see that coming after plowing through the all previous and less optimistic messages on this topic. Very happy and indeed thankful for all community efforts here!
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