There’s literally an approved solution to the problem designed explicitly to solve the problem.

Install a transfer switch so you can disconnect utility power, switch to your generator and people can see the situation at the breaker.

If you don’t have one, you use something called an “extension cord” to run power to your important devices for the duration of the outage.
If you don’t know how to power a few appliances with a generator and some extension cords, you definitely shouldn’t be thinking you can use a dangerous cable that people who do know you should never use in the first place.