I remember that alternative, free/FOSS products existed before Grafana (c2015) but many died, Grafana was everywhere. Now I also cannot find the old-alts. Vague memories of RRD and Nagios...
We're using a combination of Zabbix (alerting) and local Grafana/Prometheus/Loki (observability) at this point, but I've been worried about when Grafana will rug-pull for a while now. Hopefully enough people using their cloud offering sates their appetite and they leave the people running locally alone.
I'm out of that game now though so don't have the challenge.