Hi JerryChang,
Thanks for the suggestion, will incorporate that.
We tested the performance of other software on the newly flashed Nanos, and everything works so far. So we might as well close this topic. Thank you immensely for your support.
Just one more thing. We also need to create a signed and encrypted update files, to simply update the changes summarized in my above post, like the dtb to partition DTB, and the bootloader image to partition LNX, etc. So as to avoid flashing the Nanos each time, as they might be in a remote location. Of course this will be a prevention method rather than a cure. But I have created a separate topic for that here: How to update u-boot binary on the LNX partition for Jetson Nano without flashing.