I used a battery hand warmer to keep my hands warm it works similar to the normal ones just rechargeable. This thing got me through most of my junior year of high school. Here is the link to it on Amazon. It can also change your phone if need be.

https://www.amazon.com/FVSA-Rechargeable-10000mah-Luminescence-Electric/dp/B08KCY88RN/ref=mp_s_a_1_34?crid=FKX1T2S7CG0Z&keywords=electric+hand+warmer&qid=1642393577&sprefix=Eletric+ha%2Caps%2C189&sr=8-34