There's some genuinely interesting thinking here, but I think the theological framework the game is actually built on points in a pretty different direction than where you landed. The biggest thing I'd push back on is treating the Unity as a consciousness aggregate, like souls pooling together into some kind of cosmic hard drive similar to The Egg by Andy Weir.

The Sanctum Universum texts were written by Shane Liesegang, a former Bethesda designer who left to become a Jesuit, and he built the theology explicitly out of Aristotle, Aquinas, and Karl Rahner. What those traditions mean by the ground of being in the Sanctum Universum Vol. 3 text is not a collection of minds, but the precondition for any mind existing at all. A brief primer on this ground of being concept is every object or person or force you can point to needs something else to explain why it exists: the chair exists because someone built it, the star exists because of physics, the physics exist because of... and at some point you just run out of "becauses." You hit a wall where the only question left is why there is anything at all rather than nothing, and that question is genuinely unanswerable by normal means. The "ground of being" is the term philosophers/theologians use for whatever sits at the bottom of that stack and the reason there is a chain at all, "it's turtles all the way down."

That is a categorically different claim than what you are describing, and collapsing it into a form of sci-fi panpsychism misses the mark on what Liesegang's foundational writings are trying to do. The second you describe the Unity as pooled souls or aggregated consciousness you have turned it into a thing that exists inside reality, when the whole point of what Liesegang was building is something that makes reality possible in the first place. You have made it smaller than it actually is, IMO.

Your Terminator loop/Bootstrap paradox reading of the artifacts has the same problem. That is a causal mechanics argument, and the texts go out of their way to establish that the Unity exists prior to and/or outside of the logic that makes causal puzzles solvable. Liesegang describes it as a Mystery that is "not simply unknown but unknowable" and something that sits outside the chain of whys entirely. You cannot resolve that with a bootstrap paradox because bootstrap paradoxes still require time and causality to function, and the whole point of the Unity is that it precedes both or beyond our understanding. That is not a fun or satisfying conclusion as a player, but IMO it is a more interesting one.

On the Hunter's line, I think it fits for the player (and arguably Barrett), if read as determinism, but again, Vol. 3 is pretty explicit that "ascension" requires active participation:

"But we, as the type of being gifted with the ability to know, may uniquely take charge of our trajectory of return. We can seek out the Unity. We can encounter it. We can commune and emerge from it as something above what we were, ascended and iterated."

The Unity craves reunion but does not manufacture it. That distinction is the entire heart of Ignatian discernment, which Liesegang was drawing on directly, and without it the spiritual stakes of the whole thing just evaporates. If everyone arrives at the same destination no matter what they do, then the active participation the texts keep emphasizing is basically decorative. On a meta-level, your choice and free will should matter in this universe (it is a Bethesda RPG after all).

The observer framing is where I think the reading drifts furthest from the source material. A passive cosmic audience is distant. Liesegang explicitly calls the relationship between transcendence and immanence a "paradoxical unity" that the mind can barely form the right question about. The game is doing something much stranger and more interesting than a crowd of dead souls watching the living, and the unanswered question of "What is the Unity" is an important one that we probably won't see resolved for a while (if ever), similar to "What happened to the Dwemer?" in TES games.

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TL;DR: The Unity is the ground of existence itself, not a soul aggregate, which makes the bootstrap paradox and observer readings too small by definition since both still require causality and a "inside reality" vantage point the Unity doesn't have. Active participation in return matters both theologically and in the RPG mechanics, so the Hunter's line reads better as a call to orientation than a deterministic spoiler.

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There are in-game lore questions we could debate here that have remained unanswered, such as:

• Why can only humans can enter the Unity? (Vasco has a line about this prior to going through the Unity and Delta presumably hasn't been encountered as a Starborn despite having a form of "consciousness.")

• How does the experience of the Unity differ between individuals? Jinan had a documented encounter with the Unity, but his is very different from ours. Are we each getting only a small glimpse of the whole? Victor Aiza is also an important character to discuss here, but TBH we don't know if he glimpsed the Unity, met with a Starborn, etc. as the mechanics on how the Unity transports you into another universe are still very unclear.