I believe 1770k for Switch would be the best December of this generation (PS4/XB1 included) so that's good.
That number likely is not what Nintendo needed to get to that 20 mill target though, you likely needed sales in the 2.2-2.5 mill range to keep that target in play.
Switch is a more traditional type of platform in its sales curve (more like the PS4 actually) and I think Nintendo is going to have to just embrace that and make sure they are selling more throughout the year, not just leaning so heavily on holiday sales.
PS4 and XB1 were somewhat weak this December.