I don't get it. If you don't trust Apple, then you don't take photos with an iPhone. There is no possible service they could offer that assures you every bit of data and metadata is obfuscated end to end in any sense of before Apple software has a chance to see it. At bare minimum, the camera app has to put together a file before there is anything to encrypt. A malicious Apple could just keep a second copy of that file, and even if you used a different backup service, they'd still have it.