Great stuff! I’ve just recently set up a Pi 3b node too, so I hope you don’t mind my adding a couple of notes.
I was initially having issues with the launch script starting NIS with too much RAM given over to it, which resulted in the JVM processes being killed by the kernel after a few hours (as logged in /var/log/kern.log), but reducing the max memory flag to
-Xmx768M seems to have done the trick.
htop shows RAM maxing out at about 856MB after running the node for ~6 hours (though it does also seem to use a little of the swapfile).
I’ve also dropped the amount of shared graphics RAM down to 16MB using the raspi-config tool, from the default 64MB, as I run it headless with no special graphics requirements/environments.
Finally, I’m a fan of using the process manager Supervisor to daemonise and automatically start/restart NIS, as it also gives you a web panel to manage processes. Handy to be able to see this on the network without needing to ssh in to the Pi.