Zabbix has been around for quite a long time. Easily 15 years now. I haven't looked at it since around 2013, but at the time it was placing quite some pressure on a mysql db backend. It looks like they've expanded out to support more than MySQL as the back-end these days.
Zabbix has been growing A LOT lately, and in a good way. It's nice to see this king of projects evolving Una good direction instead of stagnating and the diying.
It's great to hear. I liked zabbix in general. At the time of its initial surge in popularity, nginx and cacti were the dominant force in monitoring. Zabbix was a little quirky to get used to, but a breath of fresh air.
I noticed that Zabbix supports PostgreSQL and TimescaleDB as back-ends and just checked the list, which contains also Oracle and SQLite (DB2 support is experimental).