> Some panpsychists might try to actually say that there's a potential that trees and rocks have an internal subjective experience that is in some way comparable to human conscious experience

Okay well that's silly and I've not met even one panpsychist who believes this "comparable to human conscious experience" portion

> Once you even slightly disrupt the structure of our brains functioning, it all falls apart. We feel nothing.

This isn't true. You can literally cut a brain in half and you appear to get two separate consciousnesses in one skull.

> I think even most panpsychists would ...

Sure... so why are you spending so much breath attacking the obviously weak form of the argument?

> ^and if it's the second case, it's unprovable and uninteresting and "literally meaningless. Irrelevant."

There have been lots of things, in fact pretty much all of them, that were unprovable and uninteresting until they weren't. People have to work hard to build the frameworks to talk about, test, and ultimately understand the universe. That's what people are trying to do with consciousness. It can be "too early" for your tastes, but that doesn't make the endeavor meaningless.