How to create a image based OTA payload package for Jetpack 4.4?

Hello Wayne, thank you for your very quick and concise answer! I only saw that OTA was available for 4.4 so I thought the image based OTA would be available as well. Thank you for the clarification.

So, If I have an board flashed with Jetpack 4.6 (or whatever is the latest jetpack), I could imaged based OTA payload package to upgrade whatever machines I have Jetpack 4.4 on. Would I still need to perform step 12?

Also, I see that someone asked for help in creating a clone based payload package. ota customized image clone they were advised to use this command line:
sudo ./l4t_generate_ota_package.sh -f user_rootfs.img -o user_rootfs_updater.sh <board_name> <bsp_version>

the user_rootfs_updater.sh is based upon nv_ota_rootfs_updater.sh

I have read the documentation and am not sure how to customize nv_ota_rootfs_updater.sh. the documentation seems to be only 1 paragraph:

The default rootfs updater’s usage is:
nv_ota_rootfs_updater.sh [-p ] [-d ]
Where:
• is the device node path of the rootfs partition, for example, /dev/mmcblk0p1.
• is the path of the OTA work directory, for example, /ota_work.
• is the path of the rootfs image, for example, /ota_work/system.img.
If you create a customized rootfs image, you must specify a rootfs updater that can process that image. The rootfs updater you specify must expect the same arguments and options as nv_ota_rootfs_updater.sh. Your update may use these arguments and options or not, depending on your specific needs.

Do you know where I could find more documentation on how to customize nv_ota_rootfs_updater.sh? Do I really need to customize it? Or can I just use it as is?

Thanks in advance for your advice!