Why don’t you consider getting a pocketable smaller phone? You could get her a Jelly Pro, which is only a bit bigger than a watch, and even set it up with xDrip+.
If you need help, in always here.
I already have a phone, my old phone, so was just thinking of saving money. I did think of getting a cheap iphone if my phone doesn’t work out. Her preschool room is the size of a living room, so I am thinking if she had it in her backpack, it would still connect.