The 10 watt USB charger is probably OK, but how do you know it is 10 watt? What is the voltage and ampere output of this charger?
Considering the Pixel 2 comes with warnings to use only the supplied charger I wouldn't experiment with other chargers. Just return the incorrect cables and buy the correct ones. Here's a quality set that I bought:
USB Type C Cable CHOE 2Pack [3.3ft & 6.6ft] Hi-speed USB Type C to Type C(USB-C to USB-C) Charging Cable for Google Pixel 2/Pixel/Pixel XL,new MacBook,Lumia 950/950xl,Nexus 5x/6p,ChromeBook Pixel
https://www.amazon.com/dp/B01H3COF6...ag=hawk-future-20&ascsubtag=UUacUvbUpU6124035