According to Nintendo PR-
http://www.businesswire.com/news/home/20171102005773/en/Super-Mario-Odyssey-Nintendo's-Fastest-Selling-Super-Mario
The last update we got from Nintendo was 2 million (referring to September)
http://www.gamesindustry.biz/articles/2017-10-19-nintendo-switch-passes-2m-us-sales
Nintendo has increased supplies of Nintendo Switch to meet demand through the holidays. The total number of Nintendo Switch systems sold in the United States through the end of October now stands at more than 2.6 million.
http://www.businesswire.com/news/home/20171102005773/en/Super-Mario-Odyssey-Nintendo's-Fastest-Selling-Super-Mario
The last update we got from Nintendo was 2 million (referring to September)
http://www.gamesindustry.biz/articles/2017-10-19-nintendo-switch-passes-2m-us-sales