You’d have to be pumping up quite a bit I think to reverse through the residential transformer with just your little generac home unit, but you may be correct if there are no one way circuits or backfeed fuses. Even so, hopefully it wouldn’t kill. Home voltage stepped up would lose its amperage and be like an extremely anemic taser potentially.
I’d love to hear from an electrical worker on the topic, but yea, it’s the amps that kill more than the volts.