The code still lives with your preferred Git hosting provider. Xcode Cloud copies/clones the code just like any conventional CI. Once the build is done, Apple claims to remote/delete any copy of it.
> No configuration as code, no shell scripts you can run from your existing CI/CD, no ability to trigger a build remotely or push code to them on demand. You can't even synchronously wait on a build to finish - you have to set up a web server and listen for a webhook! You can't integrate it with your existing CI/CD - whether that's GitHub Actions, GitLab pipelines, etc.
I will reserve my comments about inter-op till they release their API and I get to play with it.
Xcode Cloud seems to be a blessing for iOS developers who don't have exposure to CI/CD systems. And that includes most iOS developers. And also it will be a blessing for companies since hiring good CI/CD engineers for iOS is really hard.
My personal view is, Xcode cloud does a lot of things what fastlane was doing using Apples Cloud infrastructure.