So, then, a female USB to male microUSB cable should in fact work fine? (or, in my case, I think miniUSB male to microUSB male might be what I need, since the port on the matthias is a miniUSB)

Or, perhaps, instead of double female USB, a female USB to male miniUSB adapter would allow the N810's original cable to plug into the matthias keyboard.

Either way, though, that still leaves open the need for the large display, and larger resolution on that display.