In a few weeks I will be moving to the north of Sweden where temperatures can drop down alot and warm shoes can be something to consider. I have a normal rubber boots with very thin shoe pads. I tested them outside on -5'C and they get cold very fast. So I had to do something and found a solution. I have two sleeping foam pads/mats which we dont use anymore so I decided to cut a pair of new (much warmer) shoe pads out of it.
You can see on the photo bellow the original pad is on the top of the one made of foam mat. I tested them outside last night on -9'C and it felt warm underneath the feet. Woolen socks in combi with this tick pad feels really comfortable and warm.