I'm trying to create single USB Stick containing Installer, Packages, and autoinst.xml for SLES15 GMC. Only way I have succeeded is to copy contents of Packages iso to a new folder on the Installer named packages/ and then use this media url in autoinst.xml for each package I want: <media_url><![CDATA[hd:///packages?device=/dev/disk/by-id/usb-Kingston_DataTraveler_3.0_408D5C1658F7B190394419A1-0:0-part1&filesystem=auto]]></media_url>

The UUID of this exact USB stick must be present or this doesn't work: <media_url><![CDATA[usb:///packages</media_url> won't work.
So this autoinst.xml file will only work on my 1 stick. I want to create a single iso which can be dd'd to any USB stick and used for unattended installs.

If I dd the Packages iso to its own USB stick, then start the Installer from CD-Rom, when I try to add packages and select USB, my USB stick is not seen at all (because it is iso9660?). If I run yast2 --> Add-On Products from an installed SLES15 system, and try to use this same USB stick (dd of Packages iso), it is not detected either.

The SLES15 documentation seems to indicate that a installation is possible from USB (and in the case of the Installer with no packages it is) but mentions nothing about the packages. I suppose it might work if I format a separate USB stick with some filesystem and extract the contents of the Packages iso to it, but then the install requires 2 USB sticks. I'm trying to avoid needing 2 of anything to get this done.

Any ideas?