Zabbix would be a great add to the software on dietpi. After it’s installed its all web based programming and it has no limits how many systems it can monitor.
I use it for 10+ years and it’s great indeed… but it does requires a database server with sufficient performance to manage the data, specifically housekeeping can take a lot of resources).
Personally, I think that telegraf+grafana+influx seems better suited for dietpi (and besides telegraf, it’s already in the repository).
and telegraf is something that can be installed quite easily
curl -sL https://repos.influxdata.com/influxdb.key | apt-key add - echo "deb https://repos.influxdata.com/debian buster stable" | tee /etc/apt/sources.list.d/influxdb.list apt update apt install -y telegraf
Configuration of telegraf would need to be done manually anyway
At least the zabbix-agent(2) would be a great step! Running the zabbix-server on a pi, maybe not, but the agent would be awesome to have on my nano-pi’s running dietpi!