I don't think Nintendo will even try to beat the specs of the steam deck. It's not a direct competitor anyway. Nintendo will just use hardware that is good enough for their purposes, but it won't be top notch or anything. Battery life will be more important anyway. So if the Switch 2 releases in 2023 or something, it will be on par with the Steam Deck at best if you ask me.
That said, the specs alone won't really determine which of the two is "better". That is entirely subjective. The Steam Deck will be better for me personally as I prefer the freedom I can only get on a PC. I would even prefer the Steam Deck if the Switch 2 gets a massive power upgrade over it, which is very unlikely. That said, if you love Nintendo games over all else, a Steam Deck won't do you any good with that, so a Switch 2 will be the better choice. I like both worlds, so I will get both devices anyway. And there's really no point in a direct comparison.
Official member of VGC's Nintendo family, approved by the one and only RolStoppable. I feel honored.