No one grades them at the moment unfortunately. I think the best luck we would have is petitioning CGC to start doing it, as they seem to have the best infrastructure for it being a comic book grading company.
I’m going to pretend grading postcards isn’t/won’t ever be a thing, theyre hard enough to find without adding grades into the mix hahaha
That being said, I frame mine and have them in a large array on my wall, and they look fantastic