From my limited use so far, if the dash display is set to show maps (versus the basic display without maps), then Google Maps is on the screen unless you have CarPlay connected via wire and are in navigation via Apple Maps. If CarPlay is via the dongle, then Google Maps is replaced with a black display where the map used to be. I haven't tried Waze or Google Maps running via CarPlay yet, though, to see if anything other than Apple Maps projects via CarPlay onto the dash screen. More experimentation is required ;-).
BTW, here is what it looks like with Apple Maps: