Putting aside that you're comparing GPU prices to full system prices, I'm going to write what I always write:
People buy Nintendo consoles for the Nintendo games.
Looking at it in a purely technical way is completely missing the point. Nintendo does not compete on a technical level. It does just enough to give third parties a space to put games on. That's pretty much all they need.
A family will not buy a Steam Deck. Can't exactly go to a the next store and buy one either. The Steam Deck, just as all handheld gaming PCs are niche devices.
The Xbox Series S is an all digital device and not everyone is comfy with that. Also, it only does 1080, 1440 for some games.
Don't get me started on a decent gaming PC. That's way out of the league of an average family.
PS5s are as expensive and offer few actual exclusive games. Family games are rare (the extraordinary Astro Bot being an outlier).
From that perspective... the only alternative casual consumers have to a Switch 2 is... a Switch 1?
(Also that second to last gen performance claim is weird. If Digital Foundry is to be believed, Switch 2 is a very capable machine a slight cut above PS4 with some advanced stuff in the hood. Considering that the Switch 1 was able to surprise many times on a technical level, I think it's going to be a decent enough machine. Certainly not second to last gen, which would be 360/PS3).
Wow, thank you so much for this write-up! That Selaco box looks perfect!