I guess I connected your experience with DMT simply because they were mentioned together in one article. Well, my bad. But it makes even more sense to me now -- your ordeal sounds almost 1:1 with what I could experience when I attempted to lucid dream. I could not manipulate the REM phase to the extent as to made those "Inception-like" journeys like many folks who regularly lucid dream describe, and the phases when I should theoretically be in deep sleep I was literally awake just physically nonfunctional (though it was ease to wake up from them for a moment only to immediately fall back). The whole night then felt like if I didn't sleep at all -- exhausted and quite annoyed for some reason. It felt as if I was just oscillating between hypnagogic state, REM, and some state in between (awake yet asleep with nothing except my reason working -- exactly as you describe it).

As far as hypnagogic state is concerned it can be pretty terrifying. Sometimes I can even feel as if something malevolent was touching or sitting on me -- never happens outside of hypnagogic state. That is, I had "touch" hallucinations in that state exclusively. Then again, I read somewhere that the "malevolent touch" is part and parcel of hypnagogic state (beats me, and no one seems to know why or what it is).

Thus, I give lucid dreaming a hard pass.

I've mentioned my experience because while during an average night the deep sleep phases are akin to amnesiac periods or gaps in awareness, that trip (as far as awareness goes) was completely continuous. And as I said, it was the sole such clear-cut incident I went through (most of the time I simply gradually transition into the "usual" sleep pattern). So, when I read Mandukya Upanishad for the first time few years ago, I was immediately reminded of my "journey". However, while Hindus talk about bliss, I would describe it as peace. Which is, too, misleading because it was simply absence of emotions, thoughts, etc. Probably emerging from that state goes first into what can be described as peace as mind is only slowly picking up, there's nothing to be disturbed about, and so one is rather calm. Until the usual (mind-)stuff fully restarts.

I asked about the voice because I suspected that it was that standard internal monologue we all have. It's the easiest part of the mind to switch off. It's enough to keep one's awareness on hearing for an extended period of time (several minutes) and the voice slowly subsides and eventually goes completely silent. When it does, it reveals the nature of the voice as well as thoughts and emotions both of which still happily continue.

I won't spoil it for you, suffice to say, we actually think neither in words nor images and what we call emotions is for the most part just proprioception (and both, thoughts and emotions constitute a self-reinforcing feedback loop). The voice is just the "mister obvious" always retelling what happened few hundred milliseconds ago. It's always looking at (immediate) past and it's also the part of the mind that our social biases and social conditioning attach to.

As for "ego death" -- the way it is portrayed by "spiritual" masses is so off I don't even know where to start. Your suspicion is correct, it cannot be eliminated. Well, it can, but that's called death. And although there are anecdotes of yogis who reached that state, you will find out that all of them were essentially living corpses always immersed in deep "samadhi" (e.g. the close ones have to feed such a person to keep them alive -- no different from brain death if you ask me). Certainly not a goal to strive for. If we all went for it, humanity would be done for in one generation. But AFAICT, mind (perception, emotion, though) can be (at least temporarily) "switched off", thus ego, too.

Yet paradoxically, even that my not be enough to "discover" one's consciousness. Not only the state of peace literally says nothing, but while consciously trying to be conscious of consciousness, mind has a peculiar inclination to create evermore subtle mind representations of the "subject". But -- and this is a huge but (:D) -- even a split of "quantum time" is enough to come to a permanent realization of our true nature.