Out of the games we know of so far:
Breath of the Wild (already)
Mario Kart 8 Deluxe (Probably did it at launch)
ARMS
Splatoon 2 (This could do one million on launch with just Japan alone!)
Super Mario Odyssey
Minecraft
so 6 for sure in my view.
I'm unsure about Fire Emblem Warriors.
I'm crossing my fingers that Xenoblade 2 will do it.
I dont see 1-2 Switch legging it out
Hardware Comparison Threads:
Current Thread
Is Hardware Getting TOO Powerful?
Older Threads:
PlayStation/Xbox/Switch: 2022 Edition
PlayStation/Xbox/Switch Hardware Battle: 2021 Edition!
PlayStation 4/Xbox One/Nintendo Switch: 2019 vs. 2020
PlayStation 4/Xbox One/Nintendo Switch: 2018 vs. 2019
PlayStation 4/Xbox One/Nintendo Switch: 2017 vs. 2018
PlayStation 4: 2015 vs. 2016 vs. 2017