Idk how much it would help you, but if you can source some fairly common stuff and do some mild DIY, you can make a cold pack/pad that “freezes” at room temp and lasts a super long time. It isn’t cold, more like cool water that stays cool. You could even make socks out of it, if you want. They would be weird and squishy and probably trigger some sort of sensory thing, but you COULD :p

https://youtube.com/watch?v=Nqxjfp4Gi0k