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If you want to dive in further you can sharpen your Web, Back-End and On-premise network security skills by performing exercises in HackTheBox.
For mobile security, there are multiple other tools, for instance for Android MobSF, Apktool, XPosed, Pidcat, drozer, jadx, qark, Android backup extractor, Inspeckage, House. If you need a detailed description of the tooling above check an article
of a colleague of mine
There are multiple courses on Coursera also on cloud security and cloud architecture for all major cloud service providers - AWS, Google Cloud, Microsoft, and Alibaba.
For Kubernetes, I suggest deploying several clusters, for instance using O'Reily Katacoda free labs
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