In the coming weeks, we will enable Pixel Visual Core as a developer option in the developer preview of Android Oreo 8.1 (MR1). Later, we will enable it to all third-party apps using the Android Camera API, giving them access to the Pixel 2’s HDR+ technology.
That means the Developer preview for Android 8.1 Oreo (MR1) will be available for the Pixel, Pixel XL, Pixel 2, and Pixel 2 XL in the Coming weeks. Google might also bring new features including Pixel 2 exclusive stuffs for 2016 Pixel devices along with the Android 8.1 Update.
That said, there's no exact date yet for when Google will release the Android 8.1 Operating System. We'll let you know once we get more information regarding this.