I have seen some of these. My wife is 4’4” has one that is built into her toilet. I have said this before here that she has on of those short toilets on her side of the master bath. I have thought about getting one for my crapper but every time I look I see the free blood pressure monitor and start laughing. Most that I have seen are in the $300 to $400 range.
She loves hers. She says it’s like tacking a shower every time and will say that it will do things for her that I could only try to do. But hers is part of the toilet not one of the add on ones.