Natural sciences do not allow for free will. It's really not that hard. The brain thinks, and it does so by following physical processes just like a digital computer. Only when you bring in metaphysical mumbo jumbo do you run into the kinds of problems you're having.
Natural sciences do allow for free will. To be more precise, natural sciences do not concern themselves at all with non-falsifiable theories about whether free will exists, what is “real reality”, and the like.
You are, of course, free to make such statements—but you shouldn’t try to pretend that physics backs it up, because it doesn’t. With these theories you are engaging in philosophy, and as long as you refuse to acknowledge that it will be difficult to discuss them with you constructively.
> natural sciences do not concern themselves at all with non-falsifiable theories about whether free will exists.
All natural sciences rely on the fact that "This follows from That" everywhere in the universe and that thoughts are manifestations of This following from That in the brain. In order to have a thought that doesn't follow from That, This must not follow from That in some cases because the brain magically willed that Something Else follow from That. With your theories, you are engaging in denying physics, whether you realize it or not.
Laypeople like you is why natural sciences are distrusted: you mistake natural science for another religion that you blindly ask for answers to your existential questions. You fail to notice that science does not provide those answers, but you go ahead and imagine those answers because you are too lazy to study actual philosophy—you pretend that physics backs you up even as no physicist worth their salt would make such a claim.
Yes, some scientists believe in materialistic monism. Some scientists also believe in whatever version of God (perhaps this would be news to you, but it happens all the time and there’s no paradox at all between being a scientist and religious simultaneously). However, both of the above are philosophical or theological beliefs; they can inform what natural sciences does, but not the reverse.
Natural sciences create models and make predictions that if this, then that would likely follow. However, there is never a conclusion that if “this -> that” is demonstrated then a model is “true” in some sort of absolute objective sense—the model is merely a transient metaphor, another model will replace it, and no model can ever be “true” because the map is never the territory.
