[Jetson Nano]How to boot from SD Card?

We offer SUB Kit Nano, an alternative upgraded vesion of NVIDA Jetson Nano.
You can boot SUB Nano Kit from onboard 16G eMMC. But some want to boot from SD card in order to expand larger storage.
Here is the user guide for reference.

Google Drive: Sub Kit Nano Flash Process.pdf - Google Drive

This article introduces how to make an image that can be started from emmc and

boot method from TF card under jetpack4.6, if you want to boot from eMMC then just focus on the first part