On one of their picture, it shows 7 moons wide, which is probably a good approximation (6 lines of those 7 moon images does seem close to filling the area of th

On one of their picture, it shows 7 moons wide, which is probably a good approximation (6 lines of those 7 moon images does seem close to filling the area of the sensor in their pictured representation, if you then shift some moons when the sensor lines get shorter at the top and bottom). So using your calculation it could be, approximately: 7*0.5° = 3.5° in FOV.