Heated insoles. Warm feet, even in cheap boots.
Not endorsing this particular product, it was the first one I found.
https://www.amazon.ca/Thermacell-Rechargeable-Heated-Insole-Small/dp/B007SNUYZI/ref=asc_df_B007SNUYZI/?tag=googlemobshop-20&linkCode=df0&hvadid=292975744528&hvpos=&hvnetw=g&hvrand=3523005998573081166&hvpone=&hvptwo=&...