The product numbers for devices are not captured by Jamf, and there's no way I know of to capture them. The problem is there's nothing on the device itself that stores that information. I've looked nearly everywhere I can think of for them (for a different purpose), and have done searches online, and it just isn't there as far as I can tell. It's just something Apple uses internally to track the different specific sales model information, but the Mac's themselves are not aware of that info.
Also, since the hardware specs themselves are going to be identical between the different case colors, in most cases, I don't think you can do something like, scan for CPU and other hardware data and try to determine what the external color is.
