https://wccftech.com/apple-now-offering-universal-purchases-of-ios-and-mac-apps/

Apple has released Xcode 11.4 and it allows developers to sell their iOS and Mac apps as a single purchase.

iOS 13.4, iPadOS 13.4, and macOS 10.15.4 beta are going to start a new wave of greatness for consumers as they support a new feature introduced by Apple - universal purchases. This means that developers can create an app for iOS and sell it as a single purchase with its Catalyst counterpart on the Mac.