Probably less of a focus on it because VMs have become so cheap and easy, and you can just encrypt a VM. I am refining an approach that allows for an OS to be

Probably less of a focus on it because VMs have become so cheap and easy, and you can just encrypt a VM. I am refining an approach that allows for an OS to be hidden via a different method though. Using disk encryption with the key stored in the TPM, and by default booting into a virtualized OS with no hint that it is virtualized, unless a key combo is pressed at the boot screen to boot into the real OS - after a password is entered. Doesn't protect against everything but it can protect against a lot if deniability is the goal.