The most complex system that I've seen that you could self host is the Sentry APM solution, have a look at how many services there are: https://github.com/getsentry/self-hosted/blob/master/docker-...

That's the main reason why I've gone why Apache Skywalking instead, even if it's a bit jank and has fewer features.

It's kind of unfortunate, either you just have an RDBMS and use it for everything (key-value/document storage, caches, queues, search etc.), or you fan out and have Valkey, RabbitMQ and so on, increasing the complexity.

That's also why at the moment I use either OpenProject (which is a bit on the slow side but has an okay feature set) or Kanboard (which is really fast, but slim on features) for my self-hosted project management stuff. Neither solution is perfect, but at least I can run them.