The one I have attaches under the seat, and sends a little jet of water up at what I imagine is about a 45 degree angle. It would make the opposite wall wet (with clean water) if I ever turned it on not sitting on it, which I haven’t.
Mine isn’t fancy, it doesn’t use power, just water pressure. The only setting is for front (for people without a penis) or for back (for everyone with an anus), and a knob for pressure.
You poop, and when you’re done, without getting up, you turn it on, and the jet of water shoots upward and hits you in the butt. It’s within an inch or two of the hole, and you can easily feel where it’s hitting you. A little wiggle/adjustment of your body on the seat to get it aligned (oh, you’ll know) and then you wait about 2-4 seconds. A little leaning of your body in the forward/backward axis (an inch or two, maybe) to sweep the crack, then you’re clean and you turn it off. Usually a second flush (if you’re the courtesy flush type like me) and the whole event is like it never happened.
Your hands are never involved, except to turn the knob on and off.
I don’t end up wet enough that I need TP at all—haven’t bought it in a year or more. It works more on pressure than water volume, sort of like the sprayer on a sink to rinse out a glass. Pretty much only the crack gets wet, it is more of a single focused jet than a spray. Some people like to use TP to dry afterwards, but there isn’t much water on you once you turn it off. It’s focused and it doesn’t really spray your cheeks or anything.
Mine was under $50 on Amazon. I buy one for every place I live in now, and couldn’t imagine going back. It’s night and day.
There are other kinds which are more of a sink sprayer kind where you hold the sprayer and have to do some aiming and whatnot; I have little experience with those. Mine is the squirting type that installs between the toilet seat the the ceramic bowl (“lux neo 120”).