Assuming it's the same as normal ChromeOS, it's a containerized full linux shell that will run most GUI apps in the native window manager. It defaults to Debian

Assuming it's the same as normal ChromeOS, it's a containerized full linux shell that will run most GUI apps in the native window manager. It defaults to Debian, so uses standard apt, but you can make a container with any distro if you have the know-how.