You probably have 3 options...
A.). Go to your local vinyl wrap shop and see if they have something close enough that matches well.
B.). Do your own research and find some vinyl that matches, pay a few bucks for some samples to try etc.
C.). Have some GMC logos painted to match at a local body shop.
Personally I think you’ll be hard pressed to find any vinyl that matches well. If option C I’d pi chase some nice aftermarket billet emblems instead of painting the OEM stock plastic pieces.
Good luck, let us know which route you go...