Ask HN: Use data from chest HR strap with Fitbit/etc. algorithms?

Call me crazy but I currently use sports tape to attach my Fitbit Inspire 3 to the back of my arm (like a CGM). I've been doing this for 2 years, it works great and I don't feel it at all.

I don't care for smartwatch features and pretty much only use it for sleep tracking and less so but also monitoring general heart health.

Given the lack of transparency on how FitBit (and others) infer sleep stages; it's hard to know for sure but I believe FitBit only uses heart rate data.

If that's the case, is it possible to feed data from a regular fitness bluetooth chest or arm heart rate strap into Fitbit (or similarly accurate) sleep stage inference systems?