Describe a way in which the Linux implementation of ChromeOS is “restricted”.
However, it's important to note that Linux on this device is subject to certain restrictions: It operates within a containerized environment, which limits both disk space allocation and system-wide access. Accessing the terminal requires navigating through a "virtual machine", and files are shared within the /mnt/chromeos directory. Additionally, the utilization of USB devices is layered behind the primary operating system support and Linux backups are separate from the overall operating system backups.
If you want uncontainerized Linux you have to dual-boot. I used to do that but it's difficult and no longer worth the hassle IMO.
IMO it's beside the point. Calling ChromeOS "Linux" is like calling cells "mitochondria". One could argue that the same could be said about the somewhat standard Linux desktop stack you'd find on Ubuntu or Fedora installs, and that's true. However, that's probably mostly just a consequence of the fact that Linux doesn't have an actual standard userspace. The closest it has is the defacto set of components you're likely to find in any GNU/Linux distro, and they are quite different than what you'll find when you boot up ChromeOS or Android.