Was never able to find anything similar for my OnePlus 6 so settled on the Sandstone and was generally pretty happy with it.
However, I purchased an OP7T a few days ago and was pleasantly surprised when I came across the following on Amazon UK
OnePlus 7T Case, Ultra Slim Frosted Transparent
It arrived this afternoon and whilst it may not be quite as slim as the CC-801 or the Sandstone, I think I am going to like it a lot.
The sides are not covered but the top and the corners get decent chunky protection - much more than a Sandstone.
The black disc on the back is my own magnetic one...