There are emulators on the App Store (a Commodore 64 one, for example), just none that can run arbitrary code. Each program that can be run on the emulator has

There are emulators on the App Store (a Commodore 64 one, for example), just none that can run arbitrary code. Each program that can be run on the emulator has to be approved (some built-in to the App, others available as in-app purchases).