It looks like the site search works just on the title, which is good because it avoids too many irrelevant results, but not everything with an RP2350B has RP2350B in the title, so they’re not shown when using that as the search term:
There’s currently just bare chips and the RP2350 Stamp XL showing. There should also be, at least, the Pimoroni Pico LiPo 2 XL W and maybe others:
I usually click Pico at the top of the Shop Page. Then 2350 in the Filter section.
Raspberry Pi Pico - Pimoroni
Then Filter it more if need be. ;)
That gives 30 results, at the moment, and most of them aren’t RP2350B. For some of them it’s necessary to read the page to find out which variant it is, e.g. (another one):
I think the shop would do better selling these if they made it easier for someone who’s specifically interested in the RP2350B version, to find the products that have one.
The RP2350A is only a relatively small step up from the RP2040, compared to the B version and the extra pins make it more of a challenge to make a useful form factor that exposes all of them, so finding ones that are of interest takes a bit more work.