For comparison, here is the US 3DS sales (in millions)
What's interesting about the 3DS is how it's sales trajectory shoots up very early on and then has a slow decay. It was pretty stagnant in the US for the first three years (3/31/2012 was the first full fiscal year). Moreover, a lot of its games were very front loaded with really only Pokemon and Smash in the latter years. Switch is only now just getting Pokemon and Animal Crossing, both games that will do very well. I think if you compare Switch and 3DS's sales and software, the Switch has more potential.
As an aside, I think you can tell the 3DS was propped up. Usually consoles peek in their 3rd year, but in the US it peeked in the first. This was also when it got a massive price drop. It's clear in hindsight Nintendo was propping that system up.
That's not USA, that's the whole America.
2020 predictions: NSW 25m, PS5 6m, XSX 4.5m, PS4 9m, XB1 3m
In December 2019 i predicted 21m Switch, but that was before COVID, obvius increased my predictions.