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.
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.
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.
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.