Centralized hosting control panel?

Sure, it's called Ansible :)

It doesn't provide your users with a control panel, but you could easily create one and offer it to your users as a service.

That's a very good excuse for me to learn a programming language or two. Any suggestions for a solution until then? :)

To be honest, what you are asking doesn't exist.

Eventually you will have to end up using something like cPanel, which is widely used, very compatible with current linux technologies and supports a distributed configuration (including some limited clustering capabilities). There are lots of reasons why cPanel is the leader of the most serious hosting businesses.

Look into Ispconfig. Its free and may suit your needs.

https://www.ispconfig.org/