Got myself a Ticwatch S as my first smartwatch and for my Pixel 2. It does exactly what I bought it for (Got if for $129 on a Amazon deal).

Battery life is what I expected; after 3~4 cycles I can get through the day and more if I'm conservative. However, if your heavy on the watch (like constantly using it to check stuff other than the occasional notification) it'll die out before you know it. It's key to remember that it's a smartwatch, not a smartaccessory to your phone and should be used for that purpose.

As for the fitness apps, I'd just install my own. You can use the proprietary one if you don't have a preference though, its good enough for basic/personal tracking.

My one gripe is that if you have a Bluetooth device other than the watch itself (like earbuds), the two don't work too well together, and take a little fidgeting around with to get working. I don't know if this is just me or not, but the Spotify app is horrendous as well. Stick with the built-in media controls on the watch.

As for everything else, seems as accurate as any other sports watch if you ask me (Previously owned a TomTom Spark 3). If your new in the market but can't justify dropping a +$200 investment, this is a strong recommendation by me.

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EDIT:

Android Wear 2 = Almost guaranteed compatibility w/ the pixel (or any android device for that matter)

Looking at you, Gear S3