I would love to see a plugin to get stratosphere IDS installed. I think it would add a great deal of modernization to the IDS capability in the platform. See https://github.com/stratosphereips/StratosphereLinuxIps. Anyone have expertise in creating plugins want to take a stab at this?
OPNsense is not Linux. It probably won't work.
It's python I think, and based on either Zeek or Suricata. So I think it's likely to work with some effort.
May also be able to use AIengine
https://bitbucket.org/camp0/aiengine/src/master/
So, go ahead ... :)