Apple does allow self-hosting enterprise apps, one of the main distribution methods for in-house apps is buying a license from Apple to install your own certifi

Apple does allow self-hosting enterprise apps, one of the main distribution methods for in-house apps is buying a license from Apple to install your own certification on iOS and MacOS devices which will let you basically remotely install, update and sideload in-house applications. We personally opted out of it because the user's device's security would ultimately fall into our hands and at worst we have a root kit on the user's device someone might exploit.