How can I find the accurate field of view (FOV ) of latest iPhone devices cameras?

Question

I want to get the accurate field of view (FOV) number of the iPhone back cameras, and I found a really useful iOS Device Capture Format Specifications in this question and system API method activeFormat.videoFieldOfView.

After my practical experience, I realized that the FOV numbers listed in tables are little different and more accurate than the fov number from the grammatical way using system API .

For example, the FOV number of iPhone X back camera listed in that reference is 60.983: please check the reference table here

however, the system API activeFormat.videoFieldOfView returns 69.654 :

Active Format: <AVCaptureDeviceFormat: 0x2815080f0 'vide'/'420v' 1280x 720, { 1-240 fps}, fov:69.654, binned, supports vis, max zoom:67.50 (upscales @1.50), AF System:1, ISO:24.0-960.0, SS:0.000045-1.000000>

And in my practical development, I prefer the fov number listed in reference table is more accurate.

So here are two following questions:

1. why is there difference of camera fov numbers between the system API and the reference table?

2. Since the existing reference only includes iPhone models before iPhone X, so how can I find the latest iPhone series camera reference table (iPhone Xs\iPhone Xs Max\iPhone XR\iPhone 11\iPhone 11 Pro\iPhone 11 Pro Max)?