Bidet toilet seats are a nice addition if you don't have a plumbed in bidet fixture. Most, whether specifically intended to or not, can give a sort of enema. Nothing like a bag or bulb, but can well moisten and lubricate the opening and inside a bit, easing the passage of hard, dry poo.
If you haven't pood in a week and are full of rocks... forget it. It's bag time.
But, if you are a bit constipated, relaxing on the seat, spreading the opening, and letting the water run in and out for a couple of minutes can get things going.
The above does not apply to the few bidet seats that have nozzles that actually go into the user. However, they are not sanitary, because the same internal nozzle is shared among users.
For me, their best6 use is to rinse out my bottom end after a poo. When the water goes in a bit, it helps get out the last bits of poo. This is especially useful if one is pooing loose.
Sadly, most have a very limited warm water capacity that soon gets really chilly.