Our watch moved health data over a hand-rolled BLE service with its own framing. We deleted it and implemented the same feature set as a custom MCUmgr management group instead — about forty lines of registration boilerplate, and the transport, framing, retries and client tooling came free. Here’s how you extend MCUmgr in Zephyr, what it bought us on HealthyPi Move, and what happened when we did the same thing again on HealthyPi 6 — a different SoC, a different command set, the same forty lines.
