Gadgetbridge allows automatic SQLite database export to the location you specify.Navigate to Settings -> Automations -> Auto export database, and from there you can configure the details.You can put it into a shared Syncthing folder, or something alike, or process it with Termux + Tasker. Personally, I hesitate to send megabytes of data over the wire every couple of minutes, so I rigged up a script that extracts the required metrics (for now its my steps only, the rest does not seem to be accurate) and sends a payload to my queue, where a consumer script later adds it to the DB.
Well, this path seems to be the most appropriate for what I am for.
And more to that, both mergerfs and snapraid are available out of the box in the latest stable Debian release.
Thanks for pointing me at it!