An unsupported commandline tool to take an existing iOS Simulator binary
marzipanify
marzipanify is an unsupported commandline tool to take an existing iOS Simulator binary (with minimum deployment target of iOS 12.0) and statically convert it and its embedded libraries & frameworks to run on macOS 10.14's UIKit runtime (Marzipan).
This isn't a tool to automatically port your iOS app to the Mac — moreso something to get you up and running quickly.
As an iOS Simulator app links against the iOS Simulator version of UIKit, it won't contain Marzipan-specific APIs like menu & window toolbar support. It's up to the user to know how to class-dump UIKitCore from /System/iOSSupport/System/Library/PrivateFrameworks and check for the macOS-specific UIKit APIs at runtime so the app can be a good Mac citizen.
N.B. You will still need all the relevant Marzipan-related enabler steps (like disabling SIP & AMFI) before a converted app will run with your signature.
Usage
marzipanify MyApp.app|MyFramework.framework|MyBinary