I'm trying to puload the app via command line, so I'm using xcodebuild and then i use productbuild to create the .pkg from the .app. altool is used later to validate and upload the package.

Yes, through the Xcode organiser it works fine. But I actually found the problem. Gonna post the solution here.

It would be in macOS context. The problem is that I would like to keep using WKWebView API to render the web content (I'm discarting approaches such as Electron for performance reasons).