Gotcha - disconnected / USB-templates are a bit of extra-special, no doubt there.
So - in the case that this is "off network", I'd argue, "just script your own" naming convention in a simple PS-script & then grab it out of an output file & inject it into your unattend?
You could do something like "MAC-address" based naming (to ensure uniqueness (and then worry about renaming the devices once you've got a full on Windows 10 environment, perhaps)?
I'm primarily trying to think of things that "don't use WMI" but "will be consistent & unique" ... can't think much beyond MAC-s at this point. Would that do (as a "temporary" name 'til you've got those suckers loaded up with Win-10 and up on the network perhaps?
<My thought / concern being that you MIGHT have to go through WMI to get the MAC-address ... though I suppose you could "just" run something like "ipconfig /all" and parse the output for a physical address field in a PS-script perhaps?>
Would that help?
You could "generate a random number" sort of thing and go "device-12345678" but there's no guarantee of uniqueness here (let alone consistency) ... and I tend to find that "guaranteed uniqueness" is a very worthwhile thing to pursue during the vulnerable time of Provisioning a system first time?