Thats are actually a pretty practical smart device. A smart instant read thermometer would be near useless, but the ones you’re describing replace the type that you’d leave in a hunk of meat while it roasts / rotisseries / smokes / slowcooks for hours at a time. In that case it’s super handy to be able to check the temperature to make sure it’s still at target without having to go back to the kitchen or out into the cold / rain, and they’ll actively notify your phone if either the internal temperature goes out of range or the ambient oven temperature does.