[sime2009]

I can second this suggestion.

I've been doing these GCP and GKE related courses the last few months as an experienced full-stack developer who is expanding their skill set be to fullerer-stack(?).

The hands-on "labs" might feel like you are mindlessly "following along" with the tutorial but you actually learn quite a lot. The "labs" are also safe in the sense that you can't shoot yourself in the credit card.

Yes, there are clearly some small parts of the courses which were later inserted as ads for new services, but it is not a big deal.

I do recommend learning the basics of what GCP has to offer though and not just concentrating 100% on k8s/GKE.