Oura Ring Generation 3
24/7 heart rate monitoring / 7 temperature sensors / Adapts and responds to you / Guided sessions / Sleep analysis, perfected. More here.
A really nice design and by all accounts the Oura Ring is a very capable device, much more capable than you may expect from such a small tracker.
This to me could be the beginning of the future, but obviously it has some way to go and the obvious problem of a lack of instant feedback remains.
The main issue is that $299 and a required $6/ month subscription is pushing it a bit...