Flashing multiple devices with mender installed

I m trying to create the base OS image that I can use to flash multiple Jetson Orin NX devices.

I m trying to follow the steps here Nvidia Jetson Orin L4T image Update
However, the raw image is not something that I can reuse on other devices as the disk partitioning is lost in the raw image.

Has someone the steps to create the base image for flashing many devices? Also is there any way to add environment variables to each device separately while flashing? I m looking for something similar to what Balena does. On Balena, it creates the OS to be flashed, and we have the possibility to set some env variables for devices on a single fleet.

Since mender convert doesnt work, how can i extend the method on the link for creating the image for all machines?