I don't think that is correct unless you have a very narrow "market" in mind. Both Sony, Nintendo, Microsoft and PC vendors sell gaming hardware. And both Sony, Nintendo, Microsoft and Steam own stores that sell video games. Sure, Nintendo's hardware and software has some distinguishing features. But, they still all compete for gamers attention and money.

As a case in point, it's clear that Nintendo themselves think they are competing with Microsoft, Sony, and the PC space. They pay tons of money to game developers in order for their games to not show up on Xbox, PS, and PC. That would make no sense unless there was some actual competition. I could mention Hades and Monter Hunter Rise as two recent examples where Nintendo paid money to devs in exchange for exclusivity.