FreeNAS (and TrueNAS) keep track of system alerts and can be configured to send those out via email and a few other services such as Slack and InfluxDB. The selection of these services is pretty limited. Especially limiting is the fact that it does not provide a way to call a custom script or a web service endpoint. But we can capture the alerts from the system and get them out in a roundabout way.
Freenas
FreeNAS (now TrueNAS) does not have access to FreeBSD's ports or packages. Normally extra software needs to be installed in jails. However sometimes you need software on the host itself. It is possible to copy program binaries from the jail to the host if you take care of a few things first.