OK - with some help from a colleague we have this working now...
into the 'armbian/userpatches' folder, I copied 'linux-sun8i-default.config' and 'linux-sun8i-dev.config' (from armbian/lib/config/kernel/)
then added the following to the end of the file:
#!dh
CONFIG_SECURITY=y
CONFIG_SECURITYFS=y
CONFIG_SECURITY_APPARMOR=y
CONFIG_SECURITY_APPARMOR_BOOTPARAM_VALUE=1
CONFIG_DEFAULT_SECURITY_APPARMOR=y
CONFIG_DEFAULT_SECURITY="apparmor"
CONFIG_SECCOMP=y
CONFIG_SECCOMP_FILTER=y
#!dh
(not sure this is exactly how it's supposed to be done - but the result was good...)
....
root@bananapim2plus:/home/dhoward# snap list
Name Version Rev Developer Notes
core 16.04.1 645 canonical -
hello-world 6.3 27 canonical -
root@bananapim2plus:/home/dhoward# /snap/bin/hello-world
Hello World!
root@bananapim2plus:/home/dhoward# /snap/bin/hello-world.evil
Hello Evil World!
This example demonstrates the app confinement
You should see a permission denied error next
/snap/hello-world/27/bin/evil: 9: /snap/hello-world/27/bin/evil: cannot create /var/tmp/myevil.txt: Permission denied