USA Top Sellers 04th March 2017 

PS4 Horizon: Zero Dawn 477,505 2 

NS The Legend of Zelda: Breath of the Wild 437,426 3

WiiU The Legend of Zelda: Breath of the Wild 167,885 4

Surprisingly low numbers if you ask me, so with zelda on NS at 437k, that brings the actual Switch numbers to 450-500k.

Source?

Here at VG Chartz ?

I only see up to feb 25th.
But i ll take your word for it.

Not surprised to see Horizon Zero Dawn outsell Zelda BoTW, switch version, but surprised its not by more.

Here the combined wiiu+switch zelda sales are more than HZD, and I didnt think that would happend.

Oh!

So if we include Mexico and Canada, that'd put the North American number at around 600k. Not bad at all. Especially for a system that launched in March. 
It did 329k in Japan, (source is Media Create)
So that would put it at 900kish with just North America and Japan. 
Factor in Europe and the rest of the world, and we've got ourselves well over 1 million units sold for launch weekend.

Source: http://www.vgchartz.com/weekly/42799/USA/

According to VGC Twilight Princess' first week on Wii was 432,864 units. GameCube version is unknown. So Breath of the Wild sold basically the same, though I didn't check how many days worth of sales the number represented for Twilight Princess, Breath of the Wild sales at least are just one or two days.

EDIT: Nevermind, made silly mistake, compared Global with US only, see below.

I think that's all of North America's numbers you saw for Twilight Princess.

This is U.S. only for Breath of the Wild. If we look at US only for Twilight Princess, it was 367,934 units. http://www.vgchartz.com/game/4573/the-legend-of-zelda-twilight-princess/USA/ 
So Breath of the Wild managed to beat Twilight Princess by around 70k in the US launch. Although since it released on November 25th, that was on a Saturday, so Twilight Princess only had 1 day of sales to go off of vs. Breath of the Wild's 2 days.