We helped a friend solve this problem via Teamviewer and would like to share experience here. Hope it helps if someone has the similar situation.
Cannot find 2018 GMC Sierra model on GDS2 2020.07 provided. Install GDS2 for vxdiag vcx nano gm on Windows 10 system.
You have selected the wrong software region. GMC Sierra is under GM Global 2020.07 pack.
VXDIAG GM GDS2 supports 2018 GMC Acadia, Canyon, Savana, Terrain, Yukon, Yukon XL models as well.
GDS2 is working fine on the GMC Sierra 2018.
Yes, it works. vcx nano gds2 connect to all control modules.
Done a NOX sensor reset and DPF regen without problem.
Any problem of vxdiag, welcome to join our whatsapp group for help.