Puppet supports OPNsense, as does Ansible. Zabbix can monitor OPNsense.Which aspects do you want to manage?Bart...
This depends on what you are trying to do. Puppet is a big one but designed for the hyperscalers to deploy and configure systems on mass rather than as an infrastructure monitoring system.If you're looking for an open source solution for monitoring with loads of flexibility then consider zabbix.
But i would like to run centralized updates, maybe that is possible with Puppet.