From the FAQ on the Discord:

*Does Xcode work?*

Yes and no. The Xcode GUI definitely doesn't work yet; see *Will <<Insert_Random_GUI_Application>> Work?* above. However, the Xcode CLI tools like Clang, LLDB, Git, the Metal compiler, the Swift compiler, and more do work.

*What about `xcodebuild`?*

Some versions of `xcodebuild` (e.g. 11.7) are known to work for extremely basic XIB-based macOS apps. However, the vast majority of projects do not qualify as extremely basic and aren't supported yet.