Yes exactly, birds just aren’t built that way.I can't fathom a ducks foot getting frostbite at or just below freezing. I have seen post where people have their ducks at -40 and they don't have frostbite.
I know people swear by epsom salt baths, but maybe too much of a good thing? I spend a LOT of time with my hands immersed in salty water, and if I get lazy and don’t wear gloves every time, it only takes a couple days to get dried up old man hands (I am neither old nor a man lol) and then what I’ve dubbed “handruff”.....which has been followed by severe cracking, but I usually don’t let it get that far. It hurts and it’s hard to heal, so if it’s at all analogous to the op’s duck, I feel for the poor thing!