I used the Sybex book and passed on the first try a few years ago. I do hear of many people having trouble passing it and I think the main reason I passed is that I had a strong background in Windows VM, which is just one step away from cloud. At the same time, if people have a solid understanding of VM then I think understanding containers is a small step.
After getting the CCSP I went over to Microsoft Learn for a bunch of their free training just because I wanted a deeper understanding of things. In time I will learn more about AWS so I can do an honest comparison of the two.
As is the case in IT, you have learned something so now learn five more things!