Estimates on Era put it at ~40k so that would be the 6th highest Switch opening behind BotW, MK8D, Odyssey, Let's Go & Smash.
So basically it's behind all of the system sellers but above all of the B tier titles. I'm not that surprised honestly. How did Mario Party do week one in UK?
Link to the VGChartz Discord server: https://discord.gg/2uMTaYtv
Someday you will die somehow
And something's gonna steal your carbon