I saw it. I tried to assess it without reference to the Chernobyl Incident, the PC games, "Roadside Picnic"... As you said, it was made well before any of that. So in that light, I took it (partly) to be a commentary on the meaninglessness of Soviet Secular Atheism and its efforts to quarantine/suppress any notion of transcendence or a spiritual/religious element to existence. The Zone is a place where there's life, color, beauty, mystery, meaning. Even in the ordinary things all around us.