hello lecwan,
it’s NOT supported with your use-case.
please refer to Jetson Nano FAQ
for example,
Q: My Jetson Nano is with sd card slot. Can I use it to verify secureboot?
A: No. Secureboot is only supported on production module(Jetson Nano with emmc).
please also check developer guide for Disk Encryption.
it’s only applies to: Jetson Xavier NX, Jetson AGX Xavier series, and Jetson TX2 series.
thanks