Technically it's likely an ATGames clone but those are so terrible it's not even worth it. That said, one of them (no idea which one) had the firmware hacked for better sound and already has an SD Card slot for more roms, so that one is basically already done lol.
Regarding the Nomad, with all the mods and hacks done to it now you I'm almost positive you don't need the bigger daughterboard with the controller on it. There's a lot of circuitry but I think that's from the old screen. I haven't gotten around to tracing the ribbon cable connection between the boards yet but the one on the back is a lot smaller and you could in theory make a smaller Genesis Portable.
There's been a few trimmed Genesis 3's which would be your best bet for official board portable though, yes.