No sense is waiting, now's as good a time as any.
The No-God being the Nonmen's ideal is a great conclusion. The worship nothingness/oblivion/darkness, and the No-God seems to be the embodiment of that. Can't believe I never thought of that.
If it helps, remember that chorae are
sorcerous artifacts. They were made with magic. The entire sarcophagus is probably something similar to a larger aporos artifact, and the little chorae we see act as something like an anchoring or enhancing effect of whatever aporatic sorcery is going on in there.
As you said, presumably, the No-God can only exist within Earwa. In the very least, the Inchoroi didn't know how, or couldn't in fact, make it without something like sorcery (assuming that Earwa is the only place where sorcery exists). Otherwise, they would have already had it. Their own portable no-field (if you've read Dune, that is. If not, you should do so int he month we have left before TGO

).
All things surrounding the aporos make my brain itch as well.