If you're gonna use a smartwatch, always remember to first close the pogo app and don't open it until making sure that google fit has updated your steps from the watch app.
Pokemon GO" finally corresponds to Apple Watch, I actually tried using it Review - GIGAZINE
Mobile Phone Smart Watch Auto Step Shaker Automatic Step Counter for Pokemon Go/GoogleFit Cellphone Pedometer
How to Show Steps on an Apple Watch Face
Pokemon Go leading to a 'population-level' surge in fitness tracker step counts – Stony Brook Medicine Target Fitness
Amazon.com: Phone Swing Step Counter Pedometer Compatible with Pokemon Go Poke Ball Plus Cellphone Accessories with USB Cable High Silent Version for Walking (Support 2 Phones Under 7.2 Inch) : Electronics
Mobile Phone Smart Watch Auto Step Shaker Automatic Step Counter for Pokemon Go/GoogleFit Cellphone Pedometer
Pokéwalker | //todo: add blog name
MoPei Phone Swing Device Steps Counter for Hatching Eggs in Pokemon Go And Steps Challenge, Compatible with iOS And Android : Amazon.it: Elettronica