The Switch and Xbox Series S are available on walmart site and other online retailers.
As has already been said, the Switch is above MSRP and from a reseller.
The interesting thing about the Series S is that entry says you can buy it in stores on Black Friday, which suggests that it is currently sold out in most/all of their stores. Amazon has the Series S listed at $369. Perhaps Walmart online actually has a few available in stock still or maybe they are just letting you order from their Black Friday supply early? Either way, there are not a whole lot of even the Series S available much less any of the other systems.