The Classical Determinism and The Quantum Theory - https://news.ycombinator.com/item?id=50195940
In a sense, "Indeterminism" implied by probabilities at the quantum level can be said to give rise to "Free Will" as the strict chain of cause and effect is broken at the fundamental level. Since there are multiple possible outcomes from the same starting conditions, "Consciousness" may be the causal agent (Observer?) which selects one of the possible outcomes i.e. "choice due to free will". Think of it as Physics leaving all options open for an event (within bounds) and Consciousness selecting one among the set. Since the probabilities must add up to one, at the aggregate macro level it is predictable and deterministic while being unpredictable and indeterministic at the quantum micro level.
This makes sense and is self-consistent. But you speak of one single item in the range [0.0,1.0]. Might one speak of thousands - of millions - even of multitudes ? The "aggregate macro level" can be a combinatorial explosion of beauties and horrors.
You also imply (I think) that there is a finite space (bounded) for a variable to range in. Analogous to an LLM spanning and recombining its training materials. But what of the infinite - the unknown ? Of course one might say that we as hoominz are similarly bounded - that we are a variety of wetware LLM, limited by our own training materials (i.e. genes + sensory inputs + generated mental experiences).
But being of a spiritual bent myself, I ask: Where is the foot in the door for the divine ? Knocking at the door of fundamental unknowability - as you say, "unpredictable and indeterministic at the quantum micro level". If there is an intangible, immaterial element to our existence - call it a "soul" - then we might have identified the interface where "the rubber meets the road".
Obv others have considered this question at great length and in great depth.