Is there any reason for a 400GB one instead of a 512GB one?

Since you're in NY, check this out:
SanDisk 512GB Extreme UHS-I microSDXC Memory SDSQXA1-512G-AN6MA

I know it's kinda expensive, but I think it pays itself off, especially since it supports 4K gaming (and thus, less lag/delays). Switch I think is 1080p, so it technically doesn't "need" 4K support, but the fast RW speeds are ideal.

$30 difference between 400GB and 512GB, but if 512GB is out of your budget, then yeah, 400GB would be fine. But I just thought I'd point out that there isn't a huge price difference.

I have a Lexar 128GB high speed micro SD. I just checked and it's this one: https://www.walmart.com/ip/Lexar-128...pter/153046567

Back when I got the switch in 2017, the 128GB cards were like $100, so that's the only reason I have 128 instead of 512 or whatever. I do think that Sandisk is a better quality brand, though. But I got Lexar because all the Sandisk and Samsung ones were sold out. (Everyone buying the Switch at once and buying micro SD cards at once.)