Fox Farm is at just any nursery ... They have the nutes , soil ( happy frog , ocean forest , light warrior ) . They had big bloom , Gro big , and tiger bloom. It's sold for VEGTABLES use. They didn't carry supplements but those are on amazon. Some carried DYNAGRO products as well.
As for GH , it will more likely keep its name and part of MG family. Just because most non growers wouldn't even know what are Plant Nutrients much less tie it into cannabis growing. It will become a " shelf brand " easily melded into other plant additives and fertilizers. I seen fish emulsion , seaweed extract , T5 fixtures , 100w / 150w CFLS , inline fans , ducting , aero bags , good potting soil , compost and on and on. ALL AT HOME DEPOT. It's not much of a stretch to see this line go mainstream.