Q: I have a Pixel 2 XL. What's the best power bank for me to get?
A: You will need a USB Power Delivery (PD) enabled power bank for your Pixel 2 XL. Even though USB PD is becoming a standard functionality among many newer power banks, especially ones with 20000+ mAh rated capacity levels, it remains a hit-or-miss among 10000mAh power banks. You may want to look at the specs carefully because the lower-capacity power banks sometimes offer only up to 5V/3A output from the USB-C port (per the USB-C 3.1 spec). 5V/3A (or 15W) by itself delivers quite decent power when charging a phone, but technically, it is not PD. For PD, the power bank must be capable of "talking" in the PD protocol and advertising voltage profiles at higher than 5V.
Check out our USB PD backup battery, the PowerPack 20000 for more information: https://www.zmiusa.com/collections/new-releases/products/20000-mah-duplex-quick-charge-portable-power-bank-battery-charger