acloud.guru is my #1 choice for pretty much all of the topics you mentioned. Materials there are good enough for any basic and intermediate level of certification.

For advanced/professional level courses I sometimes go for extra content. Examples here:

- https://learn.cantrill.io/ for Pro and Speciality - level courses on AWS

- https://kodekloud.com/ for k8s

Udemy would have some good materials too, but you need to be careful here... This platform would accept anyone who is willing to produce training videos, so the quality might vary. Look at the reviews and recommendations.

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