I was about to mention the same thing. A pass to make an image unique before bootstrapping it is, or should be, a well-known thing. Remember the hoo-hah over

I was about to mention the same thing. A pass to make an image unique before bootstrapping it is, or should be, a well-known thing. Remember the hoo-hah over unique machine SIDs in Windows NT. And there is of course the Freedesktop world's systemd-firstboot for making unique machine IDs in images in D-Bus and systemd.