Am I able to use a Nomad 2 port gadget on an Gio? I would like the those two ports to become universe 3 and 4? Is this possible? The console is unlock for 4 universes.
Yes, you can. Configuration of port/universe happens in Setup/System/Output.
PS: your Gio isn't unlocked to 4 universes, it might be unlocked to 2048 addresses. You can spread those addresses to as many universes as you want.
Do you know if a Gadget 2 will work as a gateway for an Eos Classic?
Gadget II cannot be used with Eos Classic or any XP console.