There's a start-up called Daplie building such a system of hardware and apps. It's open source and the founder has a focus on user-owned data and data security

There's a start-up called Daplie building such a system of hardware and apps. It's open source and the founder has a focus on user-owned data and data security. (I know several teammembers and preordered via Indigogo, but am otherwise unaffiliated.)