UEFI SysPrep apps are never launched - uefi

Question

According to the UEFI spec (Version 2.7 Errata A), section 3.1.7 ("Required System Preparation Applications"):
"The platform is required to examine all SysPrep#### variables referenced in SysPrepOrder. If Attributes bit LOAD_OPTION_ACTIVE is set, and the application referenced by FilePathList[0] is present, the UEFI Applications thus identified must be loaded and launched in the order they appear in SysPrepOrder and prior to the launch of any load options of type Boot####."
However, in experiments with a simple "hello world + press any key" UEFI app, I have not found any PC that will execute the app when I install it as a SysPrep boot variable.
For example:
Ubuntu is installed on a test PC with a single HDD, GPT partitioned, UEFI-boot.
Using EFI shell, copy a test app "hello.efi" from UFD (fs1:) to fs0:\EFI\hello.efi
Boot to Ubuntu and use efibootmgr to add a sysprep variable:
sudo efibootmgr -y –create –disk /dev/sda –part 1 –loader /EFI/hello.efi –label "hello" –verbose
Result:
SysPrepOrder: 0000
SysPrep0000* hello HD(1,GPT,f440c17d-...c72d,0x800,0x100000)/File(\EFI\hello.efi)
Reboot PC, and let it boot normally.
The "hello.efi" SysPrep app does not run before the OS starts booting.
On each PC I have tested, I verified that the EFI BootOptionSupport variable has bit 4 set (0x10), indicating EFI_BOOT_OPTION_SUPPORT_SYSPREP.
Regarding another quote from UEFI spec section 3.1.7:
"When launched, the platform is required to provide the application loaded by SysPrep####, with the same services such as console and network as are normally provided at launch to applications referenced by a Boot#### variable."
This seems to me that any EFI app that will run as a Boot#### variable, will also run as a SysPrep#### variable. Is this correct?
On each PC I have tested, the hello.efi app does run from a Boot#### variable (using same efibootmgr command as above, without "-y"), but never runs as a SysPrep#### variable.