Press and hold the button on the steering wheel until you hear the Google Assistant beep. This works whether you're connected via usb using android auto or via bluetooth. Works the same for iPhones with Siri and CarPlay. Not entirely clear, but its on p90 of your Infotainment guide under "Voice Pass-Thru"
Download MyChevrolet app, sign-in, "Key Fob" and it's called "Pre-Condition" since you aren't really "starting" the electric car.
You must have had a crappy dealer.