Is there a way to add loot in the chests generated in the Lost Cities mod? Specially guns

I created an Apocalypse Zombie world with some friends, and everything fine, but getting guns from MrCrayfish Gun Mod is hard because it looks like we have to craft it from zero, which is hard because we can't defend ourselves because we don't have any armor.
I checked on reddit that it can be done by modify a datapack, but I'm a noob in this topic. Can anyone help me, please?