I don’t think I’ve ever gotten an ad from the OS on Android. I know some manufacturers, Samsung in particular, include ads but that’s not “Android” so much as “Samsung’s shitty skin of Android.”
The closest I’ve gotten to an ad on Pixel is a thing to review new features after updates.
In theory I guess it provides better security in some ways, but certainly not all over giving you hardware and a VPN. So there’s that. But yeah, it sucks.