Absolutely. Nintendo has huge fanbase with most of them not caring about Nintendo ripping them off and Nintendo has some of the most highly regarded and iconic gaming IPs in the world and Nintendo has insane marketing budget behind the Switch 2 and the switch doubles as a home console.
I love the Deck but it's not going to outsell the Switch and I think Valve isn't interested in pulling people away from the Switch. Valve made the Deck primarily for Steam users and that's who they're targeting.
On the Steam Deck? Possible. On Steam? I guess technically possible if you add a third party game. But actually on Steam? Nintendo can't even give a tech demo out for free, I can't imagine what would have to happen for Nintendo to put their games on Steam.
You can also play Minecraft on the Steam Deck and technically you can also play Apex Legends on the Deck (if you install Windows and play through that), but all of it depends on the user being a tinkerer. But the casual gamer is not a tinkerer which means those possibilities have next to no impact on the wider market.