ShipYourReptiles.com sells shipping supplies including heat packs. In a pinch for non-shipping purposes only you can use hand or sleeping bag warmers if you wrap them in a few layers of cloth.
I have tubs I use for transporting snakes to/from the vet and they have air holes in them.
You'll have a hard time with the fish if you lose power. You'd need a kerosene heater or Mr Buddy type propane heater to raise the ambient temp in the room they're in, but good luck finding one for sale in the state today. Oh, don't forget the CO detector either.
I'm reading reports out of TX where people have been without power or subject to rolling blackouts, or no natural gas because the power companies are pulling on it, and as a result they're dealing with frozen water pipes and homes with internal temperatures around 50*F. TX also gets 25% of its electric power generation from solar and wind, and either the wind turbines are frozen or not turning because there is no wind, and it's cloudy with snow/ice covered solar panels so they're not doing anything either. You have a perfect storm of peak demand with 25% of the generating capacity knocked out.