Google is now pushing its first security update based on Android 10 for Pixel phones. Through this guide, you can download complete October 2019 security update for manual installation on Pixel 3a, Pixel 3a XL, Pixel 3, Pixel 3 XL, Pixel 2, Pixel 2 XL, Pixel and Pixel XL. Last month, we saw Google take the wraps off of its major Android 10 upgrade. While being in Beta phases for months, the final / public release tied every new feature together and made sure of a reliable experience. Building on that, new October 2019 update, brings refinements and bug-fixes. On top of newer security definitions, this update packs in various new functional changes for Pixel phones so be sure to update!
All official software updates are pushed to supported phones via over-the-air service. However, if you have rooted your phone or modified it with a custom ROM, the update service gets broken and you then need to manually update. After flashing, your phone should return to factory settings and if you don’t modify it till the next update, you will receive new builds via OTA(Over-the-air). Ahead mentioned download links are official and correspond to October 2019 update for all supported Pixel devices.

Google Pixel Security Bulletin – October 2019
List of devices compatible with new October 2019 security patch are: Pixel 3 XL, Pixel 3, Pixel 2 XL, Pixel 2, Pixel XL, and Pixel.
Prior to making these images available for manual download, Google starts pushing them directly through their update servers to compatible devices. We did see Check for Update functionality, which is built-in to the Android system, being fixed in the previous build so hopefully, it wont be causing any problems this time around. To check for an available update, go to Settings > System > System update > Check for update.

Functional Updates:
Packed within these new builds are the following improvements, in addition to new security definitions:
Connectivity
- Wi-Fi stability improvements [Pixel, Pixel XL, Pixel 2, Pixel 2 XL, Pixel 3, Pixel 3 XL, Pixel 3a, Pixel 3a XL ]
Pixel Stand
- Fix for missing notifications in Pixel Stand mode [Pixel 3, Pixel 3 XL]
Sensors
- Sensor calibration improvements [Pixel 3, Pixel 3 XL]
System
- System stability improvements [Pixel, Pixel XL, Pixel 2, Pixel 2 XL, Pixel 3, Pixel 3 XL, Pixel 3a, Pixel 3a XL]
UI
- Fix for memory drain in UI [Pixel, Pixel XL, Pixel 2, Pixel 2 XL, Pixel 3, Pixel 3 XL, Pixel 3a, Pixel 3a XL]
- Fix for missing heads-up notifications [Pixel, Pixel XL, Pixel 2, Pixel 2 XL, Pixel 3, Pixel 3 XL, Pixel 3a, Pixel 3a XL]
- Gesture navigation stability improvements [Pixel, Pixel XL, Pixel 2, Pixel 2 XL, Pixel 3, Pixel 3 XL, Pixel 3a, Pixel 3a XL]
- Fix for bootloop in certain device locale modes [Pixel, Pixel XL, Pixel 2, Pixel 2 XL, Pixel 3, Pixel 3 XL, Pixel 3a, Pixel 3a XL]
Download Google Pixel October 2019 Factory Images
Here are the download links for those who want to flash their phones manually without waiting for the over-the-air update to arrive or are currently running custom ROMs / mods:
NOTE: Pixel C has been dropped from support, there will be no further official software updates for the tablet.
Download October 2019 Security Update for Pixel 3a XL: Download Factory Image
Download October 2019 Security Update for Pixel 3a: Download Factory Image
Download October 2019 Security Update for Pixel 3 XL: Download Factory Image
Download October 2019 Security Update for Pixel 3: Download Factory Image
Download October 2019 Security Update for Pixel 2 XL: Download Factory Image
Download October 2019 Security Update for Pixel 2: Download Factory Image
Download October 2019 Security Update for Pixel XL: Download Factory Image
Download October 2019 Security Update for Pixel: Download Factory Image
NOTE: If installing these factory images on your Google Pixel or Nexus devices, you also need the latest fastboot tool. You can get it from the Android SDK Platform-Tools package, which you can download here.
[Via Android, Pixel Security Bulletin]