Those neurons firing while imagining are material, yes.
If the extra thing dualism adds is just behaviours of matter, how is that different from materialism?
We say that we can experience thinking about an Apple, or imagining an Apple. I see no reason why a computer, or other physically implemented AGI system, could not do that. I suspect the act of imagination is just generating, processing and transforming a computational model abstracting the thing being imagined.
I believe brains are physical objects, so therefore physical objects can imagine Apples.
I can make the computer imagine Quake for me, then fiddle with its plane of imagination for some sweet wallhacks.
You can't touch fourier transforms either, but a human brain or a microchip can compute them.
Using vaguely-defined words to support a deist position is a time-honored tradition, but isn't particularly interesting or convincing.
A collection of neurons can build a model of the world that includes its experience of apples, and from that, dedicate some neurons to representing a particular instance of an apple. This model isn't the reality of "Apples", though, and is physically located in the brain.
Sure there is, that’s what DeepMind showed us with how to find cats in images :)
There exist many things many humans have lumped together under a single label such as "cat". Those categories are all wrong, but sometimes they're useful. Machines can also get in on the fun, just as well as humans, as you point out. There's no magic there, humans aren't special.
This has the benefit that it empirically fits how people think about it. Nobody thinks a rock has free will. Some people think animals have free will. Lots of people think humans have free will. This is everybody trying to smush a vague concept into the very simple, intuitive definition above.
Which is all to say that free will is about as relevant to any conversation as say astrology is: not one bit.