I resonate with this. I think some folks will object to the word "illusion" and it's connotations but I think it is resolved with:

1. Consciousness is a material thing (that we haven't found yet)

2. Consciousness is not a material thing (and therefore we cannot "find" it, and thus cannot be "known")

2 is the weirder proposition of course. It asserts a category of things that can't be conceived, but of course it feels like we are talking about it because we are using words to contain it. But of course, the words have no direct referent. That's the illusion.

2 is only weirder if you don't already accept non-material reality, i.e. the proposition There exist real things that are not themselves composed of matter and/or energy.

That's crossing into metaphysics, which isn't usually a welcome topic here, but the fact remains that more than 80% of the current and prior world population believes/believed in a non-material reality.

The persistence and stickiness of that belief throughout history ought to at least make us sit up and pay attention. Something's going on, and it's not a mere historic lack of scientific rigor, notwithstanding science's penchant for filling gaps people previously attributed to spiritual causes. That near-universal reflex to attribute things to spiritual causes in the first place is what's interesting - why do people not merely say the cause is "something physical we don't understand"?