Well, there's virtually no way Switch 2 will have 16 GB RAM. So that of course is already one way the Steam Deck will be superior. Switch 2 will probably have 8 GB RAM, maybe 10 GB (like the Xbox Series S). Switch 2 will probably have a slightly faster CPU and slightly better GPU.
The resolution will probably be pretty comparable. I do see Nintendo going above 720p, but not sure if they will go for 1080p. Switch 2 will probably have a 800p or 900p screen.
Overall in terms of horsepower, Switch 2 will probably be a superior device. That will be even more likely if it doesn't release until 2024 or 2025.
Lifetime Sales Predictions
Switch: 151 million (was 73, then 96, then 113 million, then 125 million, then 144 million)
PS5: 115 million (was 105 million) Xbox Series S/X: 57 million (was 60 million, then 67 million)
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima