There is https://gadgetbridge.org, which seems like a cool project but I never used it since it is Android only and don't know how good the support actually is.
To my knowledge, Apple Health is the only health/fitness data storage with end to end encrypted data, which is one of my main reasons to stay out of other fitness eco systems even if their hardware is way better.
You asked that on a post with examples of data journalism articles which are obviously not AI generated. So when you say ask about „those“ it was clear to me that you meant these examples.
I do something very similar, also with Claude and Codex, because the workflow is controlled by me, not by the tool. But instead of plan.md I use a ticket system basically like ticket_<number>_<slug>.md where I let the agent create the ticket from a chat, correct and annotate it afterwards and send it back, sometimes to a new agent instance. This workflow helps me keeping track of what has been done over time in the projects I work on. Also this approach does not need any „real“ ticket system tooling/mcp/skill/whatever since it works purely on text files.