I use my fitbit mainly to track my sleep. I don't think its readings are accurate enough to give me any scientific edge. The sleep quality measurement has about a 50% chance to fit the way I actually feel.
First thing I did after activating my subscription was cancelling it. I have no idea, none whatsoever, what possible benefit I'd have from paying ten bucks a month. Which still is much better than the Whoop membership at 265 Euros a year.
These products, IMO, are nothing but gimmicks. If they cost up to a hundred bucks and did nothing than dump sensordata you could then use in any open source or paid app to get statistics... or Excel if you were so inclined, that would be something. But no, they all sell you on the app and hide the sensordata behind that.
And I gotta say... with all the enshitification going on, software devs have now reached the same level of societal usefulness as lawyers and insurance salesmen.
I know it's not you guy who suck directly but you all keep taking money for producing shit software... so yeah, I kinda do blame you personally.