They mention a phone app on their Kickstarter page. It seems to me that a phone app is what the bulk of the market wants, with dedicated hardware appealing to a small sub-market for distraction-free writing.
Why brag about this device fitting in a pocket? Phones already do, and who is taking this but leaving a phone behind?
Also, distraction-free apps already exist for phones, tablets, and desktops. And I think phones already pair with keyboards.