[TramoreJohn]

The built-in Google Maps in my Blazer EV consistently shows my home to be about 45 miles away, although other destinations seem ok. My Android phone's Google Maps places my home precicely where it is. Why the difference?

Now I only navigate using my phone, but without Android Auto, it's frustrating to rely on that tiny screen since I can't confidently rely on the large screen's guidance.

Assuming you have reset the infotainment fitainment screen and gone into Google maps and reset your home location, I think its time to call OnStar.
BTW, does your garage door opener button still show up when you pull into your driveway?