Adding Debian packages
We don't recommend duplicating eMMC / clone from one device to another. There are few scripts that run at the first time at startup and configuration files are generated which are unique to the SOM. If you have packages, add your list of packages to build script, while building roofs.
install git, and vim set the line to
readonly G_USER_PACKAGES="git vim"
If you have your application to be installed on your rootfs:
lines as an example and install your applications, config files / settings etc.
Don't forget to copy your resources to variscite folder.