I piss sitting down plenty and always have (sometimes I just want to sit and relax a bit, you know? Or sometimes you feel like you've got a fart in the mix but aren't entirely sure it won't be a shart, so you sit just to be safe) but I do find it doesn't quite empty me out as well. Standing's better, like, anatomically, for some reason.
Studies have shown that there is no difference for healthy adult males, but sitting is actually better for evacuation as you start to get an enlarged prostate (Roughly half of men over 50).
Lovely, maybe I'm getting one of those way younger than I'm "supposed" to, LOL. I think the first time I noticed a (small, but non-zero) difference between the two was in my late 20s.
You still splash when sitting. You'd need to measure it to know what results in less aerosol exposure (particularly considering the distance-to-face factor), even though it probably doesn't matter anyway. And anyone who has ever cleaned toilets knows that the women's room is not a paradise of cleanliness.
https://www.theunconventionalroute.com/men-pee-sitting-down/ or just search using terms like: men are learning to pee sitting down