https://www.developer-tech.com/news/2018/oct/23/chrome-os-oreo-favour-pie/

Analysing the latest Canary build of Chrome OS reveals it will jump from Nougat to Pie, skipping the Oreo version of Google’s system.

For a while now, Chrome OS has been stuck on the Nougat (7.1) version of Android when running apps. With the release of Pie, it makes sense for Google to jump straight to its latest version.