I posit that because wimlib supports pipable WIMs that we could pipe an endless stream of QR codes to it (thus making the "installing Windows from QR codes" possible)...
I think we managed to only ever install it once successfully without error.
Also, fun semi-related fact: In my country we called 8" and 5.25" floppies "floppies", and the smaller 3.5" ones were called "stiffies" - because the larger ones were floppy, and the smaller were, well, stiffer. Do with this information as you please.
I believe it worked by supplying the recovery software as a bootable ISO image in ROM on the drive and emulating a bootable (USB? SCSI?) CD-ROM drive at boot.
In the late 90s I worked in the server support line for DEC, and the number of times we had to talk people through the "invisible F6 prompt" was nuts.
This process was specific to installing storage drivers needed for the system volume. All other driver installation happened elsewhere.
My memory says there was actually a "Press F6 to load system storage drivers" prompt or something displayed by the installer, but it wasn't displayed for all that long a time and I imagine it was effectively invisible for many people. I recall spamming F6 to make sure I wouldn't miss the prompt.
Here's how I remember it: The Windows CD itself had drivers built into the installer so that it could discover hardware. However, if you had a brand new storage controller, you might find that even Windows NT CD's installer wouldn't recognise it, so it would tell you that there were no storage devices found. To get around this you had to press F6 right at the start of the CD boot, before the Windows logo appeared. After a few seconds you could provide your storage drivers on a floppy disk, and the Windows installer program would continue to load. This time, the installer would recognise your disks. Then during the installation you would get a visible F6 prompt to provide your storage drivers. This allowed you to provide extra storage drivers that would be bundled with the installed OS.
Most people didn't know about the first F6, because I think NT installer had some sort of very basic, generic storage drivers that would work in most cases. If you had some very recent array controller, you would likely need to know about the "invisible F6 prompt".