ok so i saw a mod that was throwing out a camo jacket of some sort.
and there are plenty of weapons cryogenics that work rucksacks etc that are already in the game. including tuff hides that help reduce damage from say sharp things :D
so the idea would be
Old military gear such as atlas rucksack
plate carriers/ think plates for this as well
clothing this would be ripstop clothing
Helmets this can be anything from old steel helmets bike helmets etc
i would think that kevlar would be around as well.
Military caches you can find dig up store things in etc.
there are some really expensive air/water tight sealed cases you can buy. that can last for years and keep food and other supplies good for years on end. there also drop safe up to 15 meters say roughly 14 to 13 yards.
besides that finding some things like a m4 or a ak sks m14 acr scar xm8 g36 not to mention x amount of pistols
Hydration bladder maybe ?
and possibly building your own ghillie suit which would be taking a jacket some cording rags or burlap sticks and vegetation from the area to make one which would go over your regular clothing.
this is just the tip of what could be added military wise