Yeah but VirtualDSM talks with the real DSM to get some info about CPU, serial number, and some other things. You can't just pick it up and put it in KVM somewhere else.
You could emulate the host's side of the communication, or patch VirtualDSM.
Yeah of course. I just was thinking it's maybe a bit easier with drivers already present optimized for a VM situation. I could then patch VirtualDSM as suggested. I also looked in the DockerDSM package. It has no serialnumber check or something because there is no bootloader, but spotted an extra port connection to verify the host system.
So then the simplest way to get it going for now is your approach with the E1000 nic on ESxi 6.