No one is exclusively a switch owner under the age of 15. It’s a supplementary device and well known that most have a primary home console be it PlayStation, Xbox or pc. So it does indeed face competition; especially from similar fantasy adventures like Elden Ring (which I consider the true generational sequel to botw).
I say this even as someone who think switch is completely irrelevant to most discussions because it’s a gameboy. Unit sales still mean a lot because consumers only buy so much and limited hours to spend on which games they do. What Zelda does definitely matters.
Considering the competition this year and non stop series of AAA tentpole releases starting with Zelda, Diablo, street fighter, Starfield, bg3 etc… into Spider-Man. To sell 20 million in a single year; especially this one with global populations facing crippling inflation. I dunno… these numbers are amazing