...Source for the first Bayonetta selling 2 millions between PS3/360/PC/Wii U? I remember the original PS3/360 release being at 1.3 millions shipped back in Q1 2010. Also, it was an incredibly overshipped game to boot, so much that in UK it could be found at £18 two weeks after its release. And the phenomenon wasn't unique to UK.
EDIT: Having checked again, the big price cuts started around Week 6, 2010, so around its fifth week on the market. The point still stands though.
The Steam version is already at 400k according to steamspy. Add in the WiiU release and any extra they shipped on PS3 and 360 and 2m is about right.
MCV actually posted what's the difference between Bayonetta 2 Switch and Bayonetta 2 Wii U for the first week
https://www.mcvuk.com/business/fifa-18-back-on-top-with-switch-sales-up-494
We know Bayonetta 2 on WiiU was around 10k. (I think that was the range)
So ~7.5k for the Switch version.