My 2020 with a 5.3 isn't even an AT4 and has the 10 speed, although won't be offered in 2021.
https://gmauthority.com/blog/2020/12/2021-gmc-sierra-5-3l-v8-and-10-speed-automatic-combo-axed-from-sle-and-elevation-trims/
https://www.lingenfelter.com/mm5/merchant.mvc?Screen=PROD&Product_Code=L011271517
This is the closest I know of. It only says 3/36 warranty on the supercharger assembly, I'm guessing it voids your GM warranty.