I am writing this for those considering GOS where you have to use a Pixel - or you need to upgrade your Pixel as a current user. I have a 6a running GOS and a 6 running Android.
Now, a lot of this is personal preference. I never use cell phone cases as I want a sleek, not bulky phone for my front pocket. So without a cell phone case, the Pixel 6 is a lot heavier than the 6a b/c it has a glass backing while the 6a is plastic backing. They actually look the same, but the 6a is a lot less slippery and weighs less without the glass backing. The plastic backing looks just as good as the glass backing.
That's it. Otherwise pretty much the same phone. 6a a little smaller and slightly less on specs, but still real solid. 6a scrolls smoother, and that could be GOS. 6a is a less expensive obviously, but you can get them pretty cheap if you can live without the longer Android security updates of the 7/7a. If I were to buy now, 7a for same reasons as 6a. I have not really looked into the 7a, but for the price the 6a beats out a pretty similar 6, so I figure same for 7/7a. Others can chime in on the 7/7a.