Bagels and corned beef (and pastrami) are pretty much common across the US, but things such as challah , gefilte fish, kreplach, hamentashen, kugel, etc. are not as commonly known.
Funny aside, I grew up near a Polish/Lithuanian bakery that sells something called babka bread. The babka I know is something like raisin challah.
It is a very fluffy egg +yeast bread, slightly sweet (but barely sweet, most of the sweet comes from the ample raisins). Much of the year it comes as a very large round loaf, but such that it looks like a giant overflowing muffin. Close to Easter, it is sold in large braid. Slices of either shape are too big to fit in a standard toaster. The bakery version was best, but babka was also sold in the grocery stores.
When I moved, I could only find a sad kind of challah bread that isn't very good. It is sold as a small braid or a regular sized loaf (fits in a toaster), and it is denser than the challah I knew growing up. It is close to regular white bread, except it has a little egg and little food coloring. (to make it look more golden)
When I did find so-called 'babka,' it was nothing like the babka I know. It is labeled "Jewish Babka." It is a very dense, almost pastry like sweet that resembles a jelly roll. Instead of jelly though it comes in either cinnamon or chocolate flavor. It is very sweet, and dense, as if the yeast failed. I have found a few different brands, but they are all similar. blech!
We have a great Polish market, and they call themselves a deli, but they are really more what I'd call a small grocery store that specializes in Polish deli meats. (not sandwiches) The only bread they ever had was shipped rye bread and poppyseed rolls around Easter. In prior years, when I asked about babka, they looked at me like I was crazy.
Well just this past Christmas, to my great surprise they had a beautiful display of loaves of fresh bread including BIG, FLUFFY, rounds of fresh babka bread!
Well almost....their loaves only came in cheese or cherry cheese flavor. Still, I was very excited! It MADE the holidays this year! (The cheese was the same as a cheese danish.)
Incidentally, I CAN get all of the foods you list above. The other odd outlier though is rye bread. Most grocery stores do not carry it, and I have not found a bakery that sells it. Even the Jewish delis near me only offer it on sandwiches. They sell bagels, but not loaves of rye. Just this past Christmas, the market I mentioned above ALSO had fresh rye! Yipee!
On a WDW related note, I have been to the Boardwalk Deli twice. The pastrami sandwiches on our first visit were excellent, but the pastrami we had on our most recent visit was much greasier. We greatly preferred the leaner version, because the meat, dressing, and cheese together made for a rather greasy sandwich. Pastrami can be variable. It was still good quality pastrami, but next time I'd get it without any dressing or cheese.
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