Get an EV instead. Use it for bi-directional charging, buy PV to reduce your dependency and energy bill and a heat pump to be independent of oil/gas companies.
vs
EV => $8000 - $40000
Bidirectional charging infra => $2000 - $5000
PV => $5000 - $15000
Heat pump => $5000 - $10000
That's an awful lot of money that you're proposing people spend in order to cover a rare occurrence. Of course there's day-to-day value in having all of that which a backup generator cannot provide, but in a power outage, you'd probably rather just have the cheap gas generator, and maybe a $1000-ish "solar generator" (i.e. battery pack with inverter) that you can use to load-shift the generator. Run the genny during the day to charge the battery; run the fridge, lights, and phone charger from the battery overnight.
Here’s video summary https://youtu.be/ZmmhOXsIRjw?si=eZh_MCWJjhrwNpm9
The trick with Bolt EVs is that one must have the car on, because the high voltage battery will not engage when the car is off for safety reasons. Also, the car shuts off every hour of unless the seatbelt is fastened. This is not a big deal.
Be choosy about the EV, not all of them have this feature (Tesla, for instance, doesn’t last I checked). That said, after we got our Hyundai (and the vehicle-to-load adapter), I sold our generator to a neighbor. Less than a year later, we both got to test our electrical backups.
Hopefully you were going to buy an EV anyway, because a nice generator is about $1000. A Hyundai Ioniq 5 is considerably more than that.
This is underestimating the ludicrous amount of power an EV's batteries have. You can absolutely power your house for days on end using one. (Of course, that should also give us pause to think about what it means that we spend so much energy for transportation compared to household necessities.) And gasoline has plenty of problems too, like its extremely short shelf-life.
I look at the size of those, and the size of a random Tesla, and I can easily see two of these shoved into the baseboard of a Tesla, much less the larger vehicles.
I know the Ford Lightning was advertised as a potential back up power source for the home.
The real trick is getting the power out of the battery and in to the home itself. It's one thing to run an extension cord to the refrigerator, quite another to get the battery plugged into your home circuitry. That requires more preparation, as well as an electrician.
Expensive way is to get some manufacturer specific automatic transfer switch (I got Tesla's put in). The hardware is $2500 and the labor is $4K+.
I did both and used both during a recent week long outage.
So there you have it, I get about one full day. Not "days on end".
On a hot day yeah I'd be running the A/C but ideally you'd have solar to offset much of that.
Average home uses 30kwH / day. Average EV battery size 40kwh. Correct not days on end, but at least a full day to full capacity, and perhaps a few days at reduced capacity. My Ioniq 5 has an 84kwH battery so I guess I'd get a bit further.