Happy Thanksgiving, to those of you in the United States!
Wanted to put a pin into what I landed on for monitoring, at least until I find some new hotness.
So I am currently using two tools. I replaced grafana+influxdb+telegraf with grafana+prometheus+node_exporter. The only thing I have to do is have two separate dashboards for the FreeBSD and linux boxes. I am also using a tool called Beszel, that while it has many linux-isms (e.g. is happiest running under docker), the dev got me a copy built on FreeBSD. While it doesn't have a lot of BSD stats (e.g. monitoring ZFS pools/datasets, etc) it is a great tool for getting an at-a-glance status of the network. I then use grafana to get historical trends on the hosts.
So far, it is working pretty well.