I came across a few comments on other sites suggesting this show could expand into something bigger, maybe even an idol series where the girls go up against other cities like Matsumoto or Tokyo.

But I think people forget that this show isn’t really about idols, even if it dresses like one. Sure the promos featured the VAs doing real idol work, the characters sing, dance, and wear idol outfits. But Yuina and the gang aren’t idols. They’re witches. And witches grant wishes.

It’s still technically an "idol" show because of how the show is presented, but when it comes to the in-verse plot, the characters won’t do things like promoting Maebashi, becoming ambassadors, or performing on the streets. Unless Yuina and the gang decide to become real idols, of course.