I have some servers sending their telegraf data to a server in my home using the tailnet instead of opening a port on my firewall for that, to name one use case.

It has a pretty good ACL functionality, you can configure which hosts with certain tag can access certain routes.

yeah the amount of nodes I had on the public internet, when all I really needed was some internal connectivity (exactly like you have here, a machine sending logs to an internal-only loki instance, and then a grafana node that is also only internally relevant and never needs to see the public internet), etc.