Only original Bip and then successor Bip S have battery life measured in weeks, the new versions with fancy displays have already crap battery life. In my country none of the old two is sold anymore. I don't really care for health monitoring (i need smart watch only to get and read notifications), it measures heart rate, sleep, steps, sleep is quite accurate, the others can't say.
I remember there is now basically rebranded Bip with different firmware sold under different name (Bangle.js 2 or some other unknown chinese models), but nothing improved in last few years for low price in compact body. Everything else like those Casio or Garmin watch with good displays and battery life or LILYGO TTGO T-Watch-2020 are like 15mm, more than 50% ticker than original Bip.
In addition to what Markoff said, I recommend sticking with the original Bip or Bip Lite; nothing else, including other Bip models. Only those two give you access to [the world's largest library of watch faces](https://amazfitwatchfaces.com/bip/fresh).
I like Bip so much that when it failed (because of a design flaw fixed in Lite and later Bip models), I bought Bip Lite (since I never used Bip's GPS, always using the phone's instead).
I just found Garmin Approach S20, they seem relatively thin, use MIP display and should have also battery life in weeks used as smartwatch without GPS.
Do you care to comment on the smartwatch features or health monitoring one?