Same experience here: Lots of confusing mails after my submission, needed to re-submit a few times, and never received a notification about my extension going l

Same experience here: Lots of confusing mails after my submission, needed to re-submit a few times, and never received a notification about my extension going live. I wouldn't have noticed the Safari Extensions menu item without watching WWDC videos, anyway. On the Mac App Store, besides copy-pasting some Swift/Objective-C, you also need to come up with a UI for your app. It'll probably be a storyboard with a single window that lets users know how to activate your extension, but getting the details right without prior experience in Cocoa development will eat some of your precious dev time.