Can you take a quick picture?

If your granddaughter as a colder place in a house where she can move the cactus for the winter, there is a chance it will bloom. Around 5-10 degrees would be good. It doesn't have to be very bright, it will not grow then anyway. Just keep it dry when it is so cold.

She can also read up on winter rest for cacti -> https://www.cactus-art.biz/note-book/Dictionary/Dictionary_W/dictionary_winter_rest.htm