I can't imagine me worrying about a bit of pee on my hands (when out in the woods I mean) -- really the only things in it are going to be (a few) viruses that were obviously already IN your body

And like others, I don't recall that circumstance occurring many times anyhow.
I would prefer NOT to be walking around with solid waste on my fingers... but you know, I have done a fair bit of field work and fishing and stuff, and cr*pped in the woods a considerable number of times, and I do not think I can remember that ever *happening*. Maybe if I were in a desert with no rocks, leaves, grass, sticks, snow, just sand... I dunno. I've never NOT found something to wipe with, well enough to keep my hands clean.
Heck, I've even pooped in a certain number of horse stalls over the years (barns without washrooms, and yes, I took the deposit out to the manure pile and buried it, didn't just *leave* it in the stall

) and you just grab a handful of hay and sort of wind it up into a wad, and use that.
JME,
Pat