> b) Would that get around Nintendo Switch NAT issues?

Depends on the game. Animal Crossing is particularly bad in that regard - say you have two kids and they want to be able to play with one remote friend each as the host, it's impossible: it will not work without the hosting Switch being completely exposed to the Internet, and there can only be one "catch all" device configured on your router at the same time.

I get that Nintendo doesn't wish to run a STUN/TURN setup but JFC, that's penny pinching on the wrong end.