Shortly after Android Oreo release, the lucky few Pixel and Nexus users enrolled in beta started getting OTA updates to the latest versions. Google also uploaded the factory images of the few devices to the Android Developers Page for the impatient. Even Verizon started rolling out an official OTA to 8.0 today. However, Google has now put up the OTAs as well as the factory images up for download on their respective pages.
Both the Pixel and Pixel XL have two files. Each belonging to different carriers. Be sure to select the right file before you start downloading. For the uninitiated, the OTA files can be used straight away, while factory images first need the bootloader to be unlocked. Also, if you are unsure of the method (OTA), Google has a step by step procedure for you to follow.
Like always, users should also take a backup of the old ROM or data, just to be on the safe side. Apart from that, also keep battery upto 60% so everything goes on just fine.
- Google Developers (Full OTA Images)