@mrowand With SSD’s this this is only possible with SATA channels, kinda-ish:
PATA was really the only one we could always guarantee 100% of which order a drive would load up.
On PATA cards you had a ribbon with the end of the cable that plugged to the drive always being the first loaded, middle of the ribbon always being the second loaded. Channel 0 end of cable was always to be /dev/hda, middle on Channel 0 would be /dev/hdb if the end was plugged in.
With SATA you “almost” had it because of sata channels, but Serialized devices also counted against the counts (so if USB loaded first, it was possible a USB drive could take /dev/sda, /dev/sdb, etc…) So not a 100% guarantee here, which ever Serialized thing loaded first.
With nvme/pci based cards its first come first served based on how quickly the device can power on and present to the system during post. This is completely outside of FOG’s ability to control, so your method of disconnecting everything that you don’t want touched is the best result.
I know it’s not an answer one would hope for, but it currently is the best answer I think.