Narrowing FOV does make a difference as the curved edges are cropped out.I don't think the hardware in the git2 have dewarp build in, you can remove that in most editing software, but it will cost a little of the overall resolution just as it would if the camera supported it in the hardware.
Thank you both!
You can't totally remove fisheye with the 170' lens, but using narrow FOV will crop out the very curved edges. To get straight perspective, you do need the 90' lens.