Cloud security/penetration testing training/certification (AWS, Azure, GCP, ...)

I am a professional penetration tester for some years now, mainly focusing on web-, mobile- and desktop- applications. I feel like I'm lacking skills in terms of cloud security. Disregarding my impostor syndrome that comes with this line of work, I feel like I lack knowledge when it comes to AWS, Azure, GCP, Heroku, *Serverless*, Kubernetes specifics.

Thus I'm trying to find training (possibly with a certification) that addresses said topics.

So far I've come across these two:

* https://www.isc2.org/Certifications/CCSP …

aws azure certification cloud cloud security cybersecurity gcp penetration penetration testing security testing training