I thought about getting a traditional navigator to avoid even relying on phone navigation.

Well, of course all the Garmins and Tomtoms available now have "built-in wifi for updates" and often BT for phone notifications too. Sure, I could just not configure either but what if I want a navigator _without any radios_ and with controlled updates via SD card.

Maybe a dedicated Android phone in the car with offline OpenStreetMaps installed and airplane mode on is more realistic. Or some old 2nd hand navi that's still updateable.

You could use a GrapheneOS phone without SIM and OSMand for that.