Source? I've never heard of this. Maps has no relationship to the car's built-in navigation anyway.
Every car I've used with Google Maps has both, but you have to pay a fee to use the built-in navigation app.
Source: I drove one.
Second source: https://youtu.be/d8RJsXePE2M?t=28
Complaining about Google Maps on that car is like complaining about Google Maps on your Google Home screen. If you buy a car that is advertised as having Google software, you're going to get Google software.
Renault & GM, both of which demoed their AAOS version, enabled both CarPlay and Android Auto, so you could use another nav "app" with Android Automotive via projection.