The Android subsystem has become an increasingly important part of Chrome OS, but it remains based on Android 7.1.2 Nougat. Some of the improvements to Oreo and Pie would be very beneficial for Chromebooks, such as Picture in Picture, the new emoji set, Vulkan 1.1, and mouse capture. Now it seems that Google is updating the Android subsystem directly to 9.0 Pie, totally ignoring Oreo.

Chrome Story and Chrome Unboxed report that Android 9 Pie is now available on Google Pixelbook, but only on the Chrome OS Canary channel (most advanced / unstable version of Chrome OS). Among the visible changes include a new Settings app, which still looks awful on large screens, as well as a new interface for Google Assistant.

The new settings application

The updated user interface

The Chrome OS Camera app has also been completely replaced by Google Camera, according to a rumor that circulated two months ago. It's hard to know when (or if) Pie will be deployed on other Chromebooks, but upgrading the Android subsystem is probably a big undertaking and will probably take a while.