mildly interesting on stage

they have electric battery hand warmers now, batteries are going insane https://a.co/d/j3iDVzW

Yes

They had them at Masters Reykjavik
I forgot which team (but I think it was optic)

Yep, but honestly those suck. Not warm enough, magnetic area doesn't get warm(meaning you need very small hands to get heat), and battery runs out fast.