With the latest Xcode it is possilbe to comple iOS (iPhone) apps so they will run on an ARM Mac. This is NOT Catalyst. It is actually very simple and requires no special code in yourprogam.
However it seems to run only as an iPhone6 (very tiny image on a full size computer monitor). You do have the option of clicking the “green ball” and going full screen, but that disables any other app/monitors on your system.
Does any know if there is a way to tell the app, to use a different default device template (say iPhone 14) when running on macOS?