In Squad, sensitivity is dependent on FOV.
Making ADS sensitivity permanently equal for non-scope and scope weapons is not a good idea, scope weapons are designated for long distance, where you need precision, while non-scope weapons should be use in CQB where targets are bigger, so you don't need precision but mobility.
You can try lower ingame sensitivity and increase DPI, so sensitivity will be the same but pixel skipping lower, so it will be more precise.
Or you can just get used to lower sensitivity completely.
When using non-scope weapons at longer distance, don't forget to focus. It will lower your FOV, thus lower your sensitivity.
Then you can use more complicated tricks like changing dpi on the fly or changing sensitivity in different situations, which don't seem practical.
The easiest solution would be to add sensitivity sliders for ADS and Zoom.
Another solution would be to change how zooming works, for instance it could zoom with non-scope weapons while ADS, so when you focus it would be already zoomed and you would only hold the breath, just lke on scope weapons.
Another problem, when you increase fov, it will increase ADS FOV as well, so another slider would fix this.
Also, sensitivity could be FOV relative only while ADS, not from the hip.