Capcom updated their million sellers page.
http://www.capcom.co.jp/ir/english/finance/million.html
At the end of September 30, 2018
MHXX (3DS, DL) was at 1.8 million units
At the end of December 31, 2018
MHXX (3DS, NSW, DL) is at 3.0 million units.
So this confirms that MHXX Switch version became a million seller since launching to the rest of the world on August 2018.
http://www.capcom.co.jp/ir/english/finance/million.html
At the end of September 30, 2018
MHXX (3DS, DL) was at 1.8 million units
At the end of December 31, 2018
MHXX (3DS, NSW, DL) is at 3.0 million units.
So this confirms that MHXX Switch version became a million seller since launching to the rest of the world on August 2018.