I've heard of a few that do the litter box...we actually use washable pee pads that I bought from T. Bumpkins & Co. She is here on YT. I love them. Cute, and we don't have to change them very often. We have 2 that we just got about a month ago, and I am ready to buy some more. Gonna wait until after Christmas though....would rather buy for Sophie's SB and for the family. Here is the link to her webpage.
Washable and reusable dog and puppy pee pads, belly bands, and diapers at T. Bumpkins & Co.