"I wasn’t denying the possibility of knowing it somehow"

I wasn't implying that. I argued that you don't need different domains for all that experiential stuff to happen. You may need specializations of yourself, but that's still sort of you.

"It looks like there are different domains or layers to it - but it could also be due to how one thinks about it"

Indeed, it really looks like how one thinks about it. It's not exactly set in stone. On the other hand, some lines are drawn pretty objectively, so I get where you're coming from.

"everything must be within something else"

Until it doesn't. Then again, that's no thing. Yet, it is that which is all things. Miracle, if you ask me. Still, there's where the search stops because one finds.

All of that is verifiable and repeatable (internally demonstrable), and you cannot mistake it, because you simply cannot mistake yourself for something else -- you know when you recognize yourself.