ChromeOS forces an Google-dictated immutable VM image ("termina"). Inside this VM, in LXD containers, you get to run whatever you want. You can have multiple VMs, but they're all the termina image. You can get a shell in the termina VM, but it's pretty pointless, and all useful things are inside the LXD container.

When the hardware supports it (most often true these days), you can run nested virtualization: KVM (inside LXD) inside KVM. That will get you an arbitrary VM image.

They might relax the "Termina VMs only" policy later, but that depends on a bunch more security spending.