When I was a kid, I delivered papers on foot in Fairbanks. It was frequently 50 below (F) or colder. What worked best were felt shoes - all felt except for the heel, the upper felt about 1/4" thick, and with 2-3 pair of wool socks inside. These of course only work in a dry cold. I think the reason they worked so well was that it was easy for foot moisture to escape, so socks and all stayed dry. My feet would stay warm all day outdoors in these shoes. I have no idea if similar footwear is still available - this was 55 years ago.