I was asking myself the same. As everyone talk about these I used them until I discovered ChekMK, and others.
Now I'm no longer using Grafana and Prometheus...
To have informations on my phone home, to easily, from anywhere check/monitor my servers and ssh on them.
I selfhost CheckMK, as I'm not a Grafana fan, these tools are fine to monitor and get alerts but don't have apps...
I switched from Grafana to CheckMK I love how we can create custom scripts and agents are so easy to install.