I know that you can technically get your game to work on macOS. But that's not the same as selling it on the macOS app store. For that you need to put it in Xcode.
I recently put up a game for pre-order on the iOS app store (not made with C3) and I was surprised to see that the macOS app store sales are about 75% of the iOS sales.
Im not sure if Scirra can make the cordova plugin for macOS official, but it would seriously help. Having IAP work with macOS would also be good too.