Firmware looks like implementation detail from a distance, but it shapes the real product experience. Boot time, recovery behavior, power state, latency, and failure handling are user-facing even when the user never sees the code.
That makes the interface between hardware behavior and software intent especially important.
Good firmware is not just correct in the happy path. It is explainable when the system is stressed, observable when the device is remote, and small enough that future engineers can reason about it.
The most useful systems work often looks quiet from the outside. The device simply behaves.