Oh, I'm an idiot. I didn't realize you were just shortening it.
I can't imagine how licensing hardware out would even work.
It could literally just be a second GPU or something, much like a streamlined version of Crossfire setups on PC.
If you have a home NX maybe SCD upgrades the graphics to 2K-4K resolution.
If you have a portable NX, maybe buying a SCD upgrades the system to home NX quality so you don't neccessarily have to buy the console.