Google started to roll out the stable version of Android 8.1 Oreo update for supported Nexus and Pixel devices with December 2017 security patches, added features, improvements, and bug fixes. Android 8.1 Oreo incremental OTA (over-the-air) update started to appear on devices and this will update the device to build number OPM1.171019.011. Meanwhile Android 8.1 Oreo system images and OTA files are now available for manual installation.
Android 8.1 Oreo includes various changes, such as Neural Networks, Autofill framework enhancements, Android Go memory optimization, and others. Also, you can now enable ‘Visual Core’ image-processing chip in the Pixel 2 and Pixel 2 XL, which helps you capture high-quality photographs.
Along with Android 8.1 Oreo release, Google announces ‘Android Oreo Go’ edition meant for entry-level devices with 1 GB or less RAM. This optimized Android Oreo OS offers great performance on these devices. It includes optimized versions of Google apps, which requires less memory, less storage space, and less mobile data.
Stable build of Android 8.1 Oreo (build number OPM1.171019.011) is now available for Google Pixel 2, Pixel 2XL, Pixel, Pixel XL, Pixel C, Nexus 6P, and Nexus 5X.
Android 8.1 OTA update files and system images are now available for download. If you prefer manual installation, then you can download and install the firmware right now.
How to download and install Android 8.1 Oreo update
OTA files Installation Guide
Note: To install Oreo 8.1 OTA update manually, your device should be running on Android 8.0 Oreo stable version.
1. Download Oreo 8.1 OTA update zip file for your device from here.
2. Move the downloaded firmware OTA zip file to your device’s memory.
3. Now, boot your phone into recovery mode. To do so, switch off your phone, then press and hold the Volume Up + Volume Down + Power buttons simultaneously until you see the fastboot screen.
4. From fastboot screen, select recovery using power button and press the Volume Up key to boot into recovery.
5. From recovery, go to “apply update from external storage” using volume key and select it using power button.
6. Locate the OTA ZIP update file (you have saved on internal storage) and select it using power button. This will start flashing the OTA update on your device.
Once the update process is completed, reboot your phone. It will take some times to complete the process.
System Image Installation Guide
Note: Before begin installation you need to unlock your device’s bootloader. Also, it requires ADB and Fastboot driver setup on your phone.
Warning: This method will wipe your data completely, so back any data you have on the phone before proceeding with the below steps.
1. Download the Oreo 8.1 factory image for your device from here, unzip it and save the content inside the ADB installation folder
2. Enable ‘USB Debugging’ option on your phone and reboot your phone into bootloader mode.
3. Now go to the ADB installation folder (where you have saved the unzipped factory image) and double click the ‘
flash-all script‘. (For Windows).
4. Wait for the process to complete. Once done, the phone will reboot automatically.
Finally, you should lock the bootloader again for security. (Source)