Couldn’t find any way to add targets outside of the k3s cluster to the helm Prometheus. It seems that the helm installation is only for the targets in the kubernetes cluster environment, so it doesn’t fit my needs.
I ended up installing Prometheus with yaml(s) w/o the operator. Learned a lot comparing to the helm installation. Now I have a freedom of installing only necessary components which I understand and any target that I wish by adding them to the ConfigMap. For my small environment I do not need that enormous helm Prometheus deployment with myriads of questionable scrape jobs/alerts and metrics. This is when I started to understand Grafana/Prometheus dashboards.