Another favorite only-in-Osaka food of mine is the infamous 551 Horai.
Outside Osaka they have several stores also located in Kobe, Kyoto, Nara and Wakayama but majority are within Osaka City. No branch yet in Daito City but a few train rides away, I can find a small stall in Kyobashi Station.
551 Horai is famous for their Pork Meat Bun. But that is not only their product , they have also Ramen, Gyoza, Siomai , etc.
In their Namba and Kitashinchi (as far I know) have a small restaurant so you can enjoy 551’s delicious product while it’s steaming hot.
Although stores are only available in Kansai Area, you can always order online , and they will deliver anywhere in Japan. But for a real authentic experience try a bun or two when you are around Osaka area.