She is adorable, but...
IMO, a diaper wearing puppy indicates the puppy is not being properly housebroken. It indicates that the puppy owners would rather the puppy soil itself instead of the home. Please pardon me if I'm out of line, but a diaper wearing puppy is just sad.
If the puppy
cannot be watched, a kennel is the way to go.
Best of luck with your new puppy.