According to SuperData, the Nintendo Switch has sold over 1.5 million units worldwide. In its financial report, Nintendo said its aim was to sell 2 million units by end of March. Apparently those 2 million aren't Switch consoles sold to customers, but units shipped to retailers. Considering that the 1.5 million units from SuperData are actual sold-to-customer units, Nintendo may have already reached its 2 million target.
As far as Zelda goes, the source states that 9 out of 10 Switch customers bought Zelda.
Source, via