Yeah that's seemingly how it works. They just don't show up. But I don't really get why you can't just use the pro controller cos as I say, none of them so far have used the joycon in a way which couldnt easily be done with the pro controller (or even buttons)

I wanna say "oh, maybe they'll patch it in on a later date" but then I remember it's Nintendo we are talking about here. Though to be fair, pro-controller is one thing, a single horizontal Joycon (y'know, the "for parties" form) is another.