I'm not sure what time of year you're going, so I made a list of things I know are available regardless of festivals!
Mexico: As standard as it sounds, I love the churros with dipping sauces they have. Yummy.
Norway: School bread from Kringla Bakeri Og Kafe for sure!
China: As weird as it may sound, the strawberry red bean ice cream from the Joy of Tea is pretty delicious.
Germany: I love anything from Karamell-Küche, but a big favorite in my party is the fresh made popcorn or caramel brownie.
Italy: I feel like I don't usually stop in Italy for treats, but I do recall seeing gelato there!
USA: I don't usually get anything from this pavilion myself, although I've heard from friends the giant funnel cakes are amazing.
Japan: Sometimes they have it and sometimes they don't, but I love the mochi ice cream from the little shop outside Mitsukoshi!
Morocco: Same as Italy, I don't really recall getting sweets here, although dinner at Restaurant Marrakesh was one of my favorite meals on my last trip and the dessert I got there (Bastilla, yum!!!) was really good.
France: I can't go by France without stopping at L'Artisan des Glaces for a chocolate ice cream macaron. They've become a must have every trip!
United Kingdom: Again, same as Italy, I don't really stop here for treats.
Canada: Same as UK.
For the countries that don't have as many sweets available in carts, the shops are always likely to sell treats from the countries they represent. Japan is stocked with Pocky, and I remember the joy on my dad's face when he found HIT cookies in Germany (they were his favorite as a kid when his dad was stationed there). Hope this gives you some ideas!
