Iron(II) sulfate should be very effective against moss, and even a Fertiliser for grass, if I have understood its use correct.
But my question is it safe to use in a garden with fruit trees and vegetables?
Ferrous ( +2) or ferric (+3) sulfate will be a bit acid , but in the quantities I expect you will use , no problem. Most garden plants do well in a slightly acidic soil. Iron is present in most soils so the addition is unlikely to cause grass to grow better .