I'd highly recommend getting a proper PD-compliant battery, like this: https://www.amazon.com/Jackery-Supercharge-19200mAh-Portable-Compatible/dp/B0791BCKCS

You'd be able to charge rapidly while using your PixelBook, and it's more future-proof. At 45 Watts, you can charge most PD laptops either quickly or at a reasonable rate.