Superdata has 1.5 million Switch sales WW tracked.
So yea, it's not flying off the shelves there just isn't any of them to sell really.
By comparison in 10 days the Switch has sold half of what the PS4 sold in 1 day in NA.
If Nintendo is to be believed that means there is only 500k left to be split WW for shipments for the rest of the month.
This shit is gonna end up having a lower install base then the Wii U did after 1.5 months if Nintendo tries to keep this forced shortage going. By comparison the Wii U was at 3 mil sold at the end of december roughly 1.5 months after launch.
TLDR: Don't buy the hype of the "best launch" MS type PR Nintendo is spouting. Yea most successful launch because you shipped the most units, and now you're not shipping many more of them like usual. Interestingly enough the only launches Nintendo didn't deliberately force shortages on was the Wii U and Gamecube(Wii U had a deluxe shortage at first and Gamecube had none at all), both pretty much being their largest failures outside of the VB.