Where can I find good CNCF stack courses/materials?

Question

Cloud computing

In general, there is a problem of understanding how all this rubbish works.
Those. I can stir up some standard application deployment script into a cluster or assemble a cluster from nodes.
But sometimes there are problems like that everything seems to be on mana, but nifiga does not work. And spinning for me is now a hell of a hell of endless googling, asking people everywhere. In most cases, there is a feeling that there are very few sensible people, mostly only those who write all these things like Istio or Kubernetes.
I periodically look at turnips and scratch turnips, and whether to start reading the code. Already looked into the guts of Helm a couple of times.
In general, I am looking for sensible, but not endless material on the design of such systems, their full debugging, etc.
The task is to understand what you are doing, and not stupidly waste mana, as 100% of the courses that I have seen so far teach.
The language does not matter much, English is better, but not Hindu English. The price doesn't matter either.
The main thing is short, but clear, and without explaining what a firewall is, etc.
Istio is very necessary, it burns straight. Recently I made self-signed certificates, for ** Xia it’s just how to debug them, it doesn’t work and that’s it, no errors are visible.
K8s I'm already hacking a little bit.
But in general, one gets the impression that all these infrastructure solutions are literally crystal, you just touch it and everything falls apart.