alt Hacker NewsOne article I found[1] says that a Kroger store typically carries about 15k SKUs.
As another point of comparison: Costco themselves say[2] that they have about 4k SKUs, and state that most supermarkets have about 30k SKUs.
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Anecdotally, I can find just about everything I want, in terms of consumables, at Kroger.
Sometimes I walk over to the bodega instead. They don't have much for inventory outside of beer/smokes/soda, and their selection of actual food is both limited and expensive. But it's only a block away, so...
[1]: https://www.foodindustry.com/articles/the-largest-supermarke...
A full sized target would have about 80k skus. A small independent book store might have 25k skus stocked. A Sephora would stock 20k different skus.
I think people are underestimating the variety of products that are available.