Related to the assets, what hashing algorithm is used to produce the fileChecksum? "The signature of a file returned from the file upload step. This key is required for the public and private database." AssetDictionary. FB9826224

Here is the SPM I'm building. Note it is subject to breaking changes as I develop it. Feel free to create issues for feature requests. CloudKit Web Services SPM

magiicMedia, can you post the URL (redact your container) in here that you're using as a request or create another forum post with your issue and reference it here? I'm in the process of ripping out my private info from my repository and setting a public Github setup. Right now my solution supports Fetch + Query operations including cursors with most of the supported types. Meanwhile have a look here at some sample code: Building a CKQueryOperation URLRequest

I don't think that my reply which I marked as the answer would solve your need. Have you considered adopting Sign In with Apple? This IS supported in App Clips.