I like to go barefoot. I live in Edinburgh, Scotland, and remain barefoot all but a few days through the winter. When the puddles are frozen it is obviously below 32°F. I wrap up warm so that my body has surplus heat to dump and my feet flush with blood. My toes remain pink, wiggly and happy, and I still have them all.

Far from getting frostbite in a few minutes, I do not find 32°F unpleasant enough to be bothered putting my shoes on, even when I will be wearing them later for social reasons and have them in my bag with me.

I don't know how big a role acclimatisation plays. Perhaps if you fly in from living in Congo and try going barefoot in the Scottish winter you will get frostbite. Also Edinburgh is on the Firth of Forth and never gets much below freezing so 0°F might be a different matter entirely, I won't know.