By looking at the comments this article is creating confusion. So I thought I might provide an overview of the two things happening with ChromeOS.
1) Android apps have been enabled on many Chromebooks using a locked container that shares a Linux kernel with ChromeOS. You do NOT have access to the container mechanism that is being used. It ONLY supports a container locked by Google. It is NOT using Docker also.
This is available on both ARM and X86 Chromebooks and most recent models are now supported. It took a while.
All Android apps run in a single container.
2) Starting with ChromeOS 67 and only on Pixel books so far there is full GNU/Linux capabilities on a Chromebook without having to put the Chromebook in developer mode.
Developer mode is how you turn off much of the security of a Chromebook and keeping in this state is a bit of a hassle as when you boot you MUST remember not to hit the wrong keys and wipe your CB.
What Google has done is enable the KVM on the Chromebook ChromeOS Linux kernel. So you can run a second Linux kernel where you have full control of the second Linux kernel.
Then on top of this VM Google is pushing the use of containers. So these containers are completely separate from the Android containers.
Then all the containers on the VM share a common Linux kernel that is separate from the Android and ChromeOS kernel.
What this does is keeps the highly secure aspect of ChromeOS while giving you full GNU/Linux on the machine.
Google has also enabled forward GUI of the GNU/Linux VM to the ChromeOS desktop.
So say you start XClock on the VM the window will open up on the ChromeOS desktop.
What is also confusing to people is GNU/Linux has been available on Chromebooks for a long time. There has been a number of ways to use.
1) Put CB into developer, install Crouton and you have GNU/Linux. But to use Docker you MUST use rkt to start the containers.
2) Install the Android GNURoot app. This gives you GNU/Linux but in a fake chroot that breaks many things. You can also use the Android XSDL app for the GUI. Since Google implemented ALL Android apps in a common container the IP is the same for both GNURoot and the XSDL app.
In ChromeOS 67 Google has fixed the IPs used by the Android container and now using the NAT reserved IPs instead of private IPs. This solves a weird bug you would run into where you had a IP conflict if you used the same private IPs elsewhere.
Google is also using the NAT reserved IPs with the new GNU/Linux support through a VM.
It looks like Google will be packaging GNU/Linux applications like Android Studio in containers that you can then run on a Chromebook with just a click. But will they be in the play store is unclear. But these containers will run on the VM.
Google will have ChromeOS 67 hitting stable at the same time as Google IO where they are rumored to explain things better. All of this new GNU/Linux support with a VM is in beta.