How old are you?

But it’s a gigantic waste of energy and time when you could just download a 2mb package and be done with it.

For a handful of servers, try zabbix. Every distribution has a packaged zabbix agent. It has everything: web ui, a way to Auto discover things with a bit of setup, nice graphs, alerting, LDAP User Management if you need it, a way to define per person/group alerting/notification schedules. And the community is big enough that many common services (fail2ban/postfix/MySQL/etc.) have premade custom monitoring scripts. Adding your own metrics is also very easy.

For personal use, I don’t bother with databases on k8s. They are waaay easier to manage if you just let your host distribution run it as a regular service and Upgrade it through that