Might not be the answer you were looking for but hear me out: the biggest impact on my Kubernetes knowledge has been starting a homelab on Talos Linux.

I've used this as a sandbox/playspace/proving ground for Kubernetes concepts to satisfy my own curiosities. The benefit of this space is that you can make mistakes without affecting any real data, and you can blow away your entire config and start from scratch if you need to. I have already seen benefits to this hobby in my career.

My entrypoint was the Talos getting started guide: https://www.talos.dev/

And following the community at https://www.reddit.com/r/selfhosted/