Bullet points:

(note: all of those numbers are retail only)

- In 2017, they announced their pretty high objective of reaching two millions units sold by the end of 2018. They reached it and even surpassed it by a little bit, by selling 2.04 millions at the end of December. 1.13 millions of that number comes from 2018, versus 911k in 2017.
- They had holiday sales comparable to those of the Wii, with weeks that sold in the hundreds of thousands.
- 3DS sold 254k in 2018, versus 507k in 2017, for a grand total of 5.5 millions LTD.
- Mario Kart 8 Deluxe is the third best selling game of 2018 all platforms combined at retail. The ranking is Fifa 19 > RDR2 > MK8DX. It sold 1.2 millions LTD, with 700k of that in 2018 (so higher than in 2017). (note: it's a similar performance as in UK where MK8DX sold more in its second year than in its first)
- Super Mario Party is the fifth best selling game of 2018 all platforms combined at retail. Pokémon is seventh, Super Mario Odyssey eight and Super Smash Bros. Ultimate ninth. All of those titles sold more than 400k LTD.
- They're expecting to sell even more units this year than in 2018.

Source: http://www.lefigaro.fr/medias/2019/01/09/20004-20190109ARTFIG00413-nintendo-a-vendu-en-france-2-millions-de-consoles-switch-depuis-son-lancement.php?utm_source=app&utm_medium=sms&utm_campaign=fr.playsoft.lefigarov3

Also top seller in 2018, so PS4 sold less than 1.1m.

20% growth YOY in UK and 24% growth YOY in France. Impressive results. In Japan there wasn't such growth but maybe in USA we can expect something similar between 20-25% growth? so ending something around 5'9-6'1M for the year. That would mean 2'3-2'1M for December if my numbers are right.

Edit: Resting Japan numbers and adding 20-25% growth in the rest of the world, would mean around 15-15'5M worldwide (if we use VGC numbers for Switch in 2017), so i'm not so sure that will be the total growth...

UK+France 2017-~1.59 million
UK+France 2018-~1.95 million

459k Switch consoles sold in November-December 2017
vs
65% of their hardware number was sold in the Christmas holiday period 2018

If I remember well, 911000 was already the absolute record for any console in France for a first 10 months period.
But unfortunately, all of these numbers from every countries sound like a +25% on last year, where it needed +33% to reach 20M.

Fiscal year shipments and calendar year sales are not the same.

Jan-March could be significantly above last year and it's not unheard of for shipped vs sold difference to increase from the first year to the second.