The /Collections endpoint is not included in Qlik Cloud Services - Raw API List Request. It would be good if it were available the same way as /items / spaces etc. are included.
Useful when you would like to iterate over items in a collection (like apps with specific tag), as of know you have to do it with the Call URL basic block. I think that all public REST APIs for Qlik Cloud should be available out-of-the-box with QAA.