I'm not sure it is. I've considered getting home batteries for power outages (due to fires), and frankly given the install cost, using a car is compelling. Not only do they have enormous batteries (a model 3 has a 57.5 kwh battery and can be acquired for 20k), but they can be driven to recharge every few days if need be.

Where I'm located, in most cases when there is an outage, neighboring areas do have power.

Specifically for my model 3, I've been considering tapping into the HV system manually to keep my Ecoflow battery topped up, but I wish there was a way to directly connect it.