Privacy hardening Grafana / Prometheus ?

I have enough machines on my network that I've long wanted to get better monitoring going on, and I finally bit the bullet and I'm trying to push through learning my way around grafana and prometheus/node extension. I have been following this guide: https://grafana.com/docs/grafana-cloud/monitor-infrastructure/metrics/metrics-prometheus/prometheus-config-examples/docker-compose-linux/ (great, btw!) but after importing the dashboards so I have three dashboards providing some intense readouts of three different machines, it got me wondering: how privacy protective is this? Is Prometheus just sending out a steady stream of diagnostic data for anyone to snoop on if they get access to my LAN? How can I/should I harden these setups to be privacy conscious?