My friend is a Bible App developer in the United States. He wants to add whole King James Version Bible in his App. But we found that:
The Authorized Version is in the public domain in most of the world. However, in the United Kingdom, the right to print, publish and distribute it is a Royal prerogative and the Crown licenses publishers to reproduce it under letters patent.
As your friend wants to publish in the USA, there shouldn't be a problem with this. Technically Letters Patent are not the same as copyright, although the effect is similar. LP grant a publishing monopoly, meaning that the copyright exceptions do not apply to anything protected by LP.
I don't know how the Cambridge University Press (as the current Queen's Printer) would react to the inclusion of the King James Bible in an app, which would obviously be available to download in England and Wales, but if they were to object, I suspect they would take up the matter with Google rather than with your friend, as the dispute would just involve the distribution aspect. At most, they might try to get the app barred for download in England and Wales, although how they would ensure Scotland and Northern Ireland were unaffected is not clear. I'm not sure geo-blocking is that specific.
Advice or comment provided here is not and does not purport to be legal advice as defined by s.12 of Legal Services Act 2007