Hardware is the easy bit in the whole IoT business model. The tricky bit will be persuading people that it's something they need. For this business model to work it has to solve a big enough problem that taking the time to sign up for something like this button, getting it delivered, setting it up, and actually remembering to press it when necessary is worth the effort. That's a challenging thing to market to people - especially those who live outside of the tech industry. Which is most people.

"Build it, they will come" will not work here. Because it doesn't work anywhere.