I'd like to think of it like pseudorandom vs random numbers generators. Does it really matter if it's a truly random algo if you can't actually see any difference within the constraints of its usage?
Likewise, our pseudo-free will is probably more than enough for having near-independent agency from the environment. Anything outside of that is probably already within the realms of metaphysics, which is unprovable by definition anyway.
Although I love your metaphor for talking with people who know about RNGs and pseudo RNGs not everybody does while everyone knows about more or less accurate spheres.
And just like free will, there are no true RNGs, just RNGs that we don't have the accuracy or computer power to predict. Quantum mechanics may disprove this.
Likewise, our pseudo-free will is probably more than enough for having near-independent agency from the environment. Anything outside of that is probably already within the realms of metaphysics, which is unprovable by definition anyway.