It's hard to say in what stage of development this update is in but it's unlikely to be the final build and likely one of the interim betas leading up to it that somehow got leaked. Now, the Google Pixel 2 and Pixel 2 XL smartphones, the latest flagship smartphones right from the Google itself have been started receiving the Android 8.1 Oreo stable version, apart from the two earlier Developer Previews which the Android enthusiasts and developers might have tested and fed back.
As reported by Mashable, the Android Oreo 8.1 version is now available after several weeks of beta testing.More news: West Ham my only concern in Hart dilemma, Moyes says
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The new commands included in the Android Oreo 8.1 update include some necessary improvements in autofill functionality. Specifically, the Android Oreo 8.1 introduces a bunch of new software tools that developers will find very useful, one of those being the new Neural Networks API.
According to the report, Google Pixel XL 2 OTA measures 42.9MB in size. Up to that point, it could be hit-or-miss if checking for an update would actually do anything, even if the new software was released to the public. "The AOSP Settings app basically sends out an intent when you go into the system update section, and if you're using Google's OTA system, Google Play Services steps up and shows its UI", said Elliott Hughes in the Google+ post. After this, by following some basic instructions, you can update your device with Android 8.1 Operating System. The update will take around 10-15 minutes to get Installed on your device. You can manually keep on checking for the update as well.