oh yes, chickens poop a lot! and the bigger girls, the poop is bigger than my small dogs poops! it was shocking hah! you may want to have her in an area that is like a pen filled with bedding so you can just scoop out the poops so she doesn't always have to have diapers on? no idea your set up...
a big sandbox could work for sure, and you could also add a little wood ash in there as well. you could also give her trays of sprouted greens and she can dig and scratch them up as well.
one thing to consider is that chickens need to dig and scratch around and they need to dust bathe. it keeps them happy and healthy. maybe she can have an outdoor area to do this daily? she's very cute.