SanDisk’s 256GB microSD card is currently the highest capacity card that you can buy, and at $105 for Prime members, it’s never been cheaper. That’ll hold a lot of Nintendo Switch games.
Now, I might not buy this card unless I was planning on using all of the space, since you can get a 128GB card for $36, or 200GB for $81 right now, but that’s the price you pay for being on the cutting edge.