Simpler alternative to prometheus-alertmanager and/or graphana?

Prometheus-alertmanager and graphana (especially graphana!) seem a bit too involved for monitoring my homelab (prometheus itself is fine: it does collect a lot of statistics I don't care about, but it doesn't require configuration so it doesn't bother me).

Do you know of simpler alternatives?

My goals are relatively simple:

1. get a notification when any systemd service fails
2. get a notification if there is not much space left on a disk
3. get a notification if one of the above can't be determined (eg. server down, config error, ...)

Seeing graphs with basic system metrics (eg. cpu/ram usage) would be nice, but it's not super-important.

I am a dev so writing a script that checks for whatever I need is way simpler than learning/writing/testing yaml configuration (in fact, I was about to write a script to send heartbeats to something like Uptime Kuma or Tianji before I thought of asking you for a nicer solution).