The only part of DO-160 that is required for Class 1 hardware that is not connected to the aircraft systems in any way is the decompression test. Initially NAAs required a practical non-interference demonstration, but now they have accepted that so many iPads have been used on every type of aircraft that it is taken as read. All the rest of the requirements are for units that interface with the aircraft systems in some way.
Part of the operator approval is to show that there are adequate procedures to minimise the risk of a battery fire, and deal with one if it happens. Those procedures are already there to deal with the several hundred iPads already on board!
As several people have already said on here, iPads are the main EFB for many EASA airlines, including such small fly-by-night operators as BA, so I am not sure why you are insisting that they are not approved!