macOS versions of apps can now be included as part of a universal purchase, which allows customers to purchase a single app (or in-app purchase) that works across iOS, iPadOS, macOS, watchOS, and tvOS.
Apple says that developers can get ready to use the feature by assigning a single bundle ID for apps in Xcode and setting up their app record for universal purchase using App Store Connect.
A single purchase option for iOS, iPadOS, macOS, watchOS, and tvOS apps was added in the Xcode 11.4 beta, which was first released in February. After developers have implemented single purchase options, customers will be able to buy one app that works across all of their Apple devices.
With the option to make a purchase of an app that works on all devices, Apple is unifying the categories in the iOS App Store and macOS App Stores, so there will be minor changes coming to the categories available in Apple’s App Stores.
https://www.macrumors.com/2020/03/23/apple-universal-purchase-mac-apps/