how do i customize ubuntu 22.04 iso and rebuild it?

I am going to keep it simple. i want to create an iso which uses user-data file from a web server url while booting . for that i know i have to edit the menuentry in grub.cfg.I am using following commands from the start:

1. sudo apt update
2. sudo apt install squashfs-tools genisoimage xorriso cloud-image-utils
3. wget https://releases.ubuntu.com/jammy/ubuntu-22.04.4-live-server-amd64.iso
4. mkdir -p ~/custom_iso/iso
5. mkdir ~/custom_iso/mount
6. sudo mount -o loop ubuntu-22.04.4-live-server-amd64.iso ~/custom_iso/mount
7. rsync -a ~/custom_iso/mount/ ~/custom_iso/iso/
8. sudo umount ~/custom_iso/mount

After these step i am using following command to rebuild the iso.

mkisofs -r -V "CUSTOM_UBUNTU"
-e EFI/boot/bootx64.efi -no-emul-boot
-o ../custom-ubuntu.iso ~/custom_iso/iso/

After deploying the created ISO it says boot failed.

dont really know why is it happening.