IMO this is a sledgehammer to crack a nut.
If you want a rescue enviroment, use Kyhi's tool
Windows 10 Recovery Tools - Bootable Rescue Disk - - Windows 10 Forums
If you want to boot from a usb with full windows, use tutorial in tutoria section or use wintousb (
http://www.easyeufi.com). I do not know why OP says it does not accept isos as that is exactly what it does.
Running Windows 10 in a VM does not use native drivers of pc and no matter what anybody thinks, you do get a performance hit.
You state "The advantage of this is that the Windows VM will run on ANY machine !!".
Unless pc can be enabled for virtual technology, then this is not accurate. I believe it is possible to run vmware on pcs not vt-x enabled but they will run so slowly on old devices to make it almost impossible to use.
Also older devices may not have enough RAM and may not be possible to add extra RAM.
A "windows to go" install will run on any pc, provided there are suitable drivers.