At least in the US, a google/amazon search for electric+foot+warmer comes up with some good options. My feet are in one right now! https://www.google.com/searc

At least in the US, a google/amazon search for electric+foot+warmer comes up with some good options. My feet are in one right now! https://www.google.com/search?q=electric+foot+warmer https://www.google.com/search?q=electric+foot+warmer