Removing and cleaning windshield washer nozzles.
 

I can't find a video online showing how to remove and replace the wiper washer nozzles on a 2011 gmc sierra, or even where to buy them, or do you have to get from GMC?

I just read the official GM service information on fixing a washer nozzle and it appears the nozzle is serviced with the wiper arm as an assembly. I cannot say for sure, but most likely you'll need to get in contact with a GM dealer and have them order you the part. It's my guess that the arm and washer nozzle come as an assembly and are serviced as such.