First of all the Switch SoC is almost a 10 year old cellphone chip basically, nVidia is not making money there selling them for a few dollars each. Secondly you seemingly missed that AMD on average profits more than 2 to 1 because of volume and higher pricing. That's because Sony AND Microsoft use AMD, both. The home console market is much larger than the portable market (Sony and Microsoft usually sell twice as much as Nintendo before the shortage of PS5s etc). Even now, 450,000 home consoles sold every week versus 300,000 portables. And there is tons of supply that is on the shelves unsold for Nintendo and sales are dropping fast, meanwhile console sales are supply limited.
Your take is the opposite of reality.