Too bad it seems to not do health monitoring, my main use case of a watch now is sleep tracking with as long battery life as possible

the same for me, however I can imagine that creating a good sleep analysing software based on the hypothethical HRM and accelerometer is mission impossible. I find the best software is Garmin at the moment of writing, or at least suits me well, and it blocks me from buying any opensource watch, unless I want to have two watches on my hands