Question for people with better understanding of the technical underpinnings of iOS Message apps. I've heard people complain that Apple didn't build in app support for macOS messages, but this seems to me more a business challenge than a real technical challenge: if Apple were to create a macOS Messages app store, they'd need developers to do extra work for a relatively small target market, which probably wouldn't fly. But if they could somehow enable apps (stickers, ...) developed for iOS Messsages to run on macOS messages, that problem wouldn't exist. So, my question: how complex would it be for Apple to enable that? How big are the technical hurdles for taking an iOS targetted tic-tac-toe app and deploying it on macOS without requiring extra work from the developer?