Assuming this sensor has an aspect ratio of 3:2 (same as full frame 35mm sensor). If true, diagonal measure is 23mm, then the sensor height is 12.8mm and the sensor length is 19.2mm
Armed with these dimensions, I use conventional lens math to calculate what focal lengths will deliver an angle of view of 90° and 100°.
It’s the focal length combined with the sensor dimensions that dictate the resulting angles of view. It is industry standard to give the diagonal angle of view. This is because the diagonal measure of a rectangle is the longer of the three values which are height, length, and diagonal.
Since the diagonal is the longest of the three, the diagonal angle of view is the widest thus the one most often given. This might not make much sense but consider this industry standard is based on advertising puffing. Same for TV sets, their size is advertised based on their diagonal measurement.
That being said:
Mount a 11.5 mm lens and the angles of view will be – 58.2° vertical – 79.7° horizontal -- 90° diagonal
Mount a 9.7mm lens and the angles of view will be – 66.8° vertical – 89.4° horizontal -- 100° diagonal
It’s the focal length makes this happen, not the mount. Exception if the mount has an optical element that modifies the focal length of the mounted lens.
Formula: 35mm frame 24mm by 36mm with 50mm lens
Find diagonal = sq. root 24^2 + 36^2 = 43.27mm
Sove for angle of view
ATAN(0.4327) = 23.4 * 2 = 46.8°
ATAN is ArcTan a trig function
This formula derives the angle of view when the camera is working at infinity.
d = format dimension such as the diagonal
f = focal length
Angle of view = ATAN (d/2/f)2
An APS-C frame size is 16mm by 24mm diagonal = 28.8mm
Find angle of view if 30mm lens is mounted
Angle of view = ATAN(0.48)2
Angle of view = 25.64 X 2 = 51.28°
Perhaps someone can post this formula better. I can't remember the text book of origin, been using it for more than 30 years.