I noticed an Xcode Extension I wrote a couple of years ago isn't showing up in the Editor menu of Xcode. So I opened up the project, ran the Extension and the grayed out version of Xcode shows up but my extension no longer appears in the "Editor" menu.
So I just tried to create a brand new Xcode project, with an Xcode extension. Right out of the box, no code changes from the template, and I can't get the new project's Xcode extension to appear in the "Editor menu".
In System Preferences the app is checked off under "Xcode Extensions" but still nowhere to be found?
https://developer.apple.com/forums/thread/670068
This answers my question. A new "Xcode Extension" project right out of the box does not have "XcodeKit" set to Embed and Sign, which seems like a bug to me.