This device is a really bad idea.
I hope our resident experts will correct me here, but they appear to have moved into the life-safety realm, which is a regulatory nightmare. The product liability insurance would likely cost a lot more than their target goal.
Also, given that it would be sitting on a nightstand or countertop, I doubt it would detect a fire before the occupants had been overcome by smoke. When installing residential burglary and fire detection systems, we had to follow specific guidelines on placement and spacing to provide adequate coverage and meet regulations.
From a purely practical standpoint it seems to be self defeating: the primary purpose is to notify people when the residence is unoccupied. But, if the resident isn't there, then they likely have their iPhone or iPad with them.