This is correct, but also a lot of these machines can native boot Linux if you enable developer mode. It's not the most frictionless experience in the world, but it can work pretty well.
Edit: There's also Crouton, for an intermediate option that does need developer mode.
You can even run docker/containerd inside the LXD container.
Now the question is has anyone tried running everything above with chromeos flex inside a vm with nested virtualization!
However in my mind it was all paid back to me 100 fold when a customs officer at an international border tried to open my laptop and examine it, but was subjected to the sonic-boom beeping of dev mode boot timeout.