Skip Gran and sue Best Buy and the IoT washing machine manufacturer.

There are exactly zero big box retailers or lobbyists that will abide that.

Big box retailers seem to be able to comply with regulations mandating physical safety. Digital security requirements could be enforced by a similar system.

Because "physical safety regulations" is something that the majority understands, so it's hard to argue against that in public. With digital security, most people lack the mental models to follow the discussion, so it's really easy for lobbyists to tell them flatout lies about how those damn dems are out to take their smart lightbulbs away from them.

I explicitly formulated very carefully that this is not an issue of "people are dumb", but an issue of lack of understanding. I wish I could downvote your strawman.

Are you claiming that most people do understand computer security? My experience is that even many computer-savvy people (already a small fraction of overall population) are completely baffled by its intricacies.

Is liable? AFAIK strict liability only applies in specific cases, in general cases negligence applies. The claimant would have to prove that there was a breach of duty and a reasonable person would have done something to prevent the damage.