The Greeks use straight edged/cornered pleated pockets, so this is consistent with that. Turks, however, also use the same style for their uniforms. Both have a history of OD uniforms, but I don't know the details of either. So if you see what looks to be Greek lettering, I'm sure it's Greek.
Yes it is, I could take more photos of it if you'd like. It was supposedly bought by a Dutch guy in Lebanon who wanted an extra canteen, he sanded off most of the Israeli markings on the bottle itself. The pouch doesn't have the regular external markings, but a white label inside.
And thanks for ID-ing the jacket as 70's-80's, as that is what I as hoping it to be from, as I might make a loadout from that era sometime in the future.