Based on some similar experience: low millions per year.
Skeleton crew of devs+ITS to keep the lights on, software licensing, hardware costs, customer support, financial oversight, legal oversight and occasional compliance efforts.
Probably a good amount of technical and organizational friction involved, too, for whatever services, knowledge bases, and corporate policies were shared between the Wii U and Switch.
It seems stupid when you compare it to the fact that Pretendo probably pays about 1% as much, but that’s just how businesses work.
Age-verification HTTP requests are deeply rooted in this nation’s history.