Google just dropped Android 8.1 Developer Preview, which is pretty early and unexpected. Google released Factory Images, OTA Files and you can also download the update through the Android Beta Program.
This latest Android Oreo build is available for the Pixel 2 XL, Pixel 2, Pixel XL, Pixel, Pixel C, Nexus 6P, Nexus 5X. All builds are OPP5.170921.005. Again, this is Android 8.1 and is only in developer preview at the moment. As of right now, we have both factory image and OTA files for each device.
The final build for Android 8.1 will arrive in December and this is just the initial release. Since this is a developer preview and the first release of it, you should expect some bugs. Google says that there could be various stability issues and that some apps may not function properly (including Google apps). To read the full set of release notes before proceeding, head here.
If the beta isn’t pushing through you want to get busy manually, you can grab each image or OTA file at the links below.