Booting KaOS from a USB stick using grub 2.

I have a USB stick containing at the root level 2 directories:
/boot and /ISO.

The boot directory contains:
/boot/grub/grub.cfg (with the rest of the grub related files).
and the ISO directory contains a number of iso images for various flavours of Linux.
Among those is: KaOS-2023.09-x86_64.iso

From this USB stick I can boot a number of OS. In other word the grub2 is already installed and working.

But I cannot make KaOS boot, no doubt because my menu config is wrong. Can someone help me to solve this issue?

Here are the 2 menus I have tried (base on my own experience and on what I could find on the net) none of them working:

menuentry "KaOS" {
set root=(hd0,1)
set isofile='/ISO/KaOS-2023.09-x86_64.iso'
loopback loop $isofile
linux (loop)/kdeos/boot/x86_64/kdeosiso img_loop=$isofile kdeosisobasedir=kdeos
linux (loop)/kdeos/boot/x86_64/kdeosiso.img
}

menuentry "KaOS 2" {
set root=(hd0,1)
set isofile='/ISO/KaOS-2023.09-x86_64.iso'
probe -u $root --set=abc
set pqr="/dev/disk/by-uuid/$abc"
loopback loop $isofile
linux (loop)/kdeos/boot/x86_64/kdeosiso img_dev=$pqr img_loop=$isofile kdeosisobasedir=kdeos
linux (loop)/kdeos/boot/x86_64/kdeosiso.img
}