There are a lot more issues than you think involved in directly transferring equipment to the player, which is why people so often use the ammo box method. You need to be reasonably skilled in creating dialogs and, most importantly, to be able to have a good understanding of ArmA config just to be able to work out whether someone can carry something!
Although I never considered it when I designed it, you could use the shop interface from my
SPON Money with all items configured to cost $0. I'm still not at all sure why you can't just have a big ammo box if everything is free, but I'm sure you have your reasons; I certainly can't see that effectively re-creating the inventory menu would be worth the effort, even if you reused the BIS dialog with your own code manipulating it, since this is quite a complex thing to do when there already perfectly good ammo boxes in the game.