It looks like the GMB inventory ads have evolved from just mobile to mobile + desktop. Plus they've added a pop-up panel that shows larger format photos of listings you click on. I notice, though, when you click on the blue call-to-action words (e.g. "buy" or "learn more") you're sent directly to the VDP on the dealer's site.
I Googled a few dealership names from my desktop computer and can see some dealers' GMB panels have inventory ads, but most don't. I reckon you have to be actively participating in this project in order for the feature to work.