It also seems to work like PSN in that you can accept friend requests and not have to wait til someone inputs your friend code, and I think NNID support might come around the time the online stuff is sorted out, but we'll see. There's also the option to add on Mitomo, Facebook, and Twitter.
Otherwise it'll be a while til I get a Switch.
EDIT: Oops not by Twitter or Facebook, at least for now. But you can add with people you've played with, if you really want to add them I guess.