So this is not an e/os solution, but having two phones is really the only way to have the car entertainment screen for navigation.
The answer for me was to buy a second hand iPhone 6s and get a 6Gb data sim for £5 a month and run the wonderful Apple Maps. I know, it’s Apple but - I do believe they are better than Gugle in respect to privacy.
And I do a lot of driving so I need an up to date solution with a proper screen. And the side benefit is the phone lives in the car permanently connected all year round.
Regain your privacy! Adopt /e/ the unGoogled mobile OS and online services