How to flash kernel-dtb and kernel module without make system.img and rootfs?

Hi, jchaves,
Thank for you reply, but I didn’t find effective way to flash kernel-dtb individually in the link you provide.
Reference to this link, flash.sh cannot flash data to external devices.

My environment is :Jetson Orin NX 8GB SOM + customized carried board.
And I flash kernel+ rootfs to the NVME device ,which attach on the carried board .

Can u give me some useful command how to update kernel-dtb to NVME device with l4t_initrd_flash.sh?