The Nomad was a portable Megadrive and took the big full-size cartridges, the Gamegear was an altogether different beast, nowhere near the power or as good.
I had some Gamegear carts but never the hardware. The former handheld was quite rare and went for big cash years ago.
Woah! You've just blown my mind a bit! I never knew this was a thing until now. I'd say i'd have a look for one but I'm not sure my bank account could take it.