The Switch has the SoC of an Android tablet from 2015. That's how Nintendo can sell the switch at 200 bucks.
There's no way for valve to discount the deck, which uses a cutting edge SoC cut from the same cloth as the PS5, at anywhere near that price point.
Flagship hardware has flagship prices. If valve would have built a cheap but underpowered device to reach the price point of the switch nobody would have been interested. Gamers are into the deck because of its cutting edge specs.
Sales = f(game quality)
game quality = g(sales)
That's why if I were valve I would set about throwing money at some medium-appropriate game dev up front in addition to discounting the hardware.
OTOH I just learned the switch's battery life was not as good as I thought; it's no M1 idling. So that helps.