Why would that be ideal? I would be worried constantly about if I'm trading electricity in my house for the ability to go somewhere in an emergency. If it's such a real concern you even think about it when buying a car you should have a dedicated device.

Generators have solved this problem. My family used to lose electricity anytime there was a semi serious snow storm. We got a gasoline generator after the second time and it was always sufficient. We never needed to siphon gas from the car either. We later transitioned to a natural gas generator. The lines are all underground and tie into the existing system for the stove and dryer. No car involved.