When I first bought my pixel watch 2 I was able to optimize the settings to get almost 3 days of battery life.
A year of firmware updates later, I am back down to less than 2 days using the same settings.
I don't think the big manufacturers are going to change their ways anytime soon...
I sold my Pixel Watch 2, but I wasn't able to get two days' worth. The sacrifices weren't worth it.
Namely, you'd have to turn off the always on screen (I gave this up easily), as well as "flick to wake", which I found harder to give up.
If I were to press a button on my watch to read a notification, I may as well use my phone. YMMV.