i’d actualy go with a configuration snap for the devicename bits, there are some examples linked from my latest blog post about building self-configuring appliances at:
particulary check the links to dashkiosk-image-config and dashkiosk-client-image-config …
for enabling swap we should probably have an interface that allows access to /etc/default/swapfile (core-swapfile-control ??) you should not need to do anything but adding the SIZE= to it, a swapfile should be created on next boot automatically … i’m not sure how hard it would be to add such an interface, @jdstrand might be able to judge that, but given it would only need to allow access to that one file i imagine it would be simple and straightforward …