There’s pretty much zero chance that any of those build scenarios would happen. This is a hypothetical app for Windows, so it would be built on Windows, and it

There’s pretty much zero chance that any of those build scenarios would happen. This is a hypothetical app for Windows, so it would be built on Windows, and it would use Windows tooling. No Swift, no Objective-C, no macOS. There is no reason that Apple would drag their entire ecosystem along to build this app, if they even built it themselves.