Google uses USB Power Delivery (USB PD) as the fast charging standard in the Pixel. It can charge your phone up to 18W.
The Pixel includes an 18W USB-C PD charger from Google. As well as a USB-C to USB-C cable. Together they offer fast charging. But if you need a second charger there are cheaper options which work just as well. And Google doesn’t offer power banks for charging on the go.