Conveniently enough, I just wrote another response to the thread, since there was more I wanted to say on the topic, and it addresses this.
It’s not a matter of not having the tools to test theories of consciousness - it’s more fundamental than that. We are consciousness. When we theorize on consciousness, we are engaging in consciousness. It’s inescapable - it’s the very thing that makes it possible to theorize. And it’s entirely experiential - you necessarily experience your own consciousness and cannot possibly observe anyone else’s. We are each and all, and necessarily, behind a veil of perception. It’s literally impossible for it to be otherwise - to somehow step outside of consciousness and observe it, since the only thing that can meaningfully observe it is that same consciousness.
Yes - we can concevably at least make some good guesses regarding the physical processes that correspond with our experiences of consciousness, but that’s necessarily the extent of it. Again, it’s not simply that we don’t have the tools to do more than that, but that it’s inherently impossible for it to be otherwise.