I still don't understand why yours doesn't go up to 1.7x. Have installed a few Quest 2's now and on all of them it's 1.7x.
The Render resolution is not super sampling. For games, the render resolution is the starting point. So if you apply SS in games, it's applied to whatever Render Resolution you have selected.
As for 1.7x been the native resolution, one of the Oculus developers explained it. Lots of technobabble. But it's basically down the barrel distortion curvature of the Lenses and needing a higher resolution to counter act it. See here.
https://twitter.com/volgaksoy/status/1328145529042137088
jesus where was this link when I needed it earlier this week