I wrote an article about my long journey in the packaging, code signing, and notarization process of an Unreal Engine macOS application.
I found several problems in the recently introduced modernized Xcode workflow, and a bug in the implementation of CEF as a macOS framework.
All the detailed information is in the article - that’s quite long so I added a TL;DR section for the ones only looking for the solution.
I hope this article can help other developers and save them all the weeks I had to spend on this.