Okay, we finally have software sales up to date with march 3rd 2018, which means a whole year has passed since the Switch's release.
This is the list of million sellers after a year:
CONFIRMED MILLION SELLERS
The Legend of Zelda Breath of the Wild | Nintendo |
Mario Kart 8 Deluxe | Nintendo |
1-2 Switch | Nintendo |
Arms | Nintendo |
Splatoon 2 | Nintendo |
Super Mario Odyssey | Nintendo |
Xenoblade Chronicles 2 | Nintendo |
Mario+Rabbids Kingdom Battle | Ubisoft/Nintendo |
Pokken Tournament DX | Bandai Namco/Nintendo |
In total we have nine million sellers. Obviously Nintendo games dominate the list, even the two 3rd parties we have are using Nintendo's IPs.
There's also the case of Super Bomberman R, which was confirmed to have reached the million units at the end of March, so it may or may not count (we don't have the exact date of the milestone, so take this with a grain of salt).