Any wearable solutions where you truly own your data?

I'm wondering if there have been any efforts to developing wearables that are:

a) open source (OS hardware FTW yay!)

b) local-first — or even the type where you can choose where to store your own data.

I'm thinking:

\* Buy once, own forever (the hardware)
\* Yearly updates to the algo that makes the data useful + regular app updates via subscription model (an open source startup like Ghost, PostHog, GitLab, Supabase, Docker... etc etc.)

can data hardware local open source own privacy solutions store thinking updates wearable wearables