There are super popular and there’re stalls everywhere in Osaka that sell them.
Okonomiyaki is a savory pancake (or better known as Japanese pizza) that is filled with any ingredient you like (“okonomi” - How you like and “yaki” - grill) and usually topped with okonomiyaki brown sauce, Mayonnaise and dried bonito flake.
Takoyaki (or better known as Octopus ball) is a ball-shaped Japanese snack containing pieces of octopus traditionally but now there’s variety of ingredients to choose from. Takoyaki is originated in Osaka.

Had this in Kuromon Ichiba Market, one of the most well known food market in Osaka.