I dont think the app store for macOS has been the amazing success that the iOS one was. And Google look to be focusing on Android apps for ChomeOS as an attempt to get the app store ‘magic’ to transfer over the their desktop OS. So it’s not been easy for any of these companies on the store for desktops/laptops front as they may first have expected, and Microsoft have the additional disadvantages of having such a poor start at getting developers to embrace their app store and modern API’s etc, not to mention they have no mobile platform momentum to leverage.