I really want this for sleep tracking.<p>There are so many devices, each have their own algorithm for sleep tracking and the device I pick largely depends on the accuracy of the device's sleep tracking.<p>However there are new apps, like Nukkuaa, an (EU only) sleep analysis app that uses any heart-rate tracker (like a bluetooth fitness chest strap) and infers sleep quality from the data.<p>A generic app expands what devices are available to me. Right now I use CGM tape and stick a Fitbit Charge 3 on my tricep - but I dislike the Fitbit app and if I change to another brand I cannot export my logs.<p>A third party app has the potential to train against more data than any individual single brand could and, with appropriate tagging, could possible offer better accuracy. Open source would be icing on the cake.<p>Additionally, it would be great if devices like the Fitbit Charge could be used as a bluetooth heart rate monitor that can be used on apps that consume trackers on a (presumably) standard API (like TrainerRoad, Zwift, etc).<p>- <a href="https://www.nukkuaa.com/en" rel="nofollow">https://www.nukkuaa.com/en</a>