Or as a way for someone putting malware on the system to keep other malware away…

It can be just like you’ve said. You can also run tailscale directly on the system hosting a service and access it directly over the tailscale network.

Just use Snapraid & MergerFS. No special Hardware required and you don’t need to change what is on your disks.

From a quick search: https://perfectmediaserver.com/02-tech-stack/snapraid/

This is how I do it. No striping, normal partitions, different hard drive sizes, pretty easy. This way makes upgrades super easy too. Currently running 76TB mergerfs with 2 14TB Snapraid parity drives.

This is the best answer I’ve seen in this whole thread. You’re right that the key is not needed. Microsoft identified your system components and did the original activation based on the hardware you’ve got on your computer. All you need to do to bring back a licensed copy of Windows is to reinstall it.

On Debian, you have to be root or a sudoer. Those commands are there, just not in the path of regular users.