#qugu

Yep! Here's some in-game voice lines and explanations from Act 2:

1:

Ikora: The Witness is dead. There was no predicting what would come next. But this is what we know… When the Witness fell, the Black Fleet's eons of salvation and death… surged. Its Darkness merged with the Traveler's Light. Formed first into memory… and then into shape. This impossible object, this Echo of the fleet's victims, holds immense power. And it was left for anyone to find. The Echo grants the ability to compel. To control. To command. And with it, the Conductor has the potential to turn their threat into our annihilation.

2:

Ikora: Genocide. Thousands of civilizations across the universe, all visited by the Black Fleet. All lost to the violence of the final shape. That's where this Echo comes from. At least, that's our theory. Reports from the Pale Heart, readings on the Valence emanating from the Traveler... Everything we faced when we stared down the Witness and broke its fleet. At first, we didn't know what to call them. But Echoes seemed apt. Memories from the victims of the Pyramids, held by the Darkness... then coalesced by the Light into artifacts as sharp and fatal as their pain. If Darkness is memory, and Light is form... What else could they be? But... there's still so much we don't know. Is this the only one? What forgotten people gave form to this Echo? What was their final cry at their end? For control? A means to turn back their oppressors?

Obviously we, the players, know from Dynasty. Maya mentions it directly in a radio message, revealing her "ally" as Te'Qal:

Commander Te'Qal's strength was their individual perspective. Their skill at directing an army, not a hivemind. The Echo of Command and I were equally shapeless before we joined. It reformed my consciousness even as I made it into my mantle. Power joined to individual will: this is the key. Commander Te'Qal lacked one, and the Witness lacked the other. I hold both.

I think there will be some connection between the Qugu and the current story in some way, since we got the page for finishing Act I and I believe it should be somehow relevant. It's possible that it's not, but I feel like it should be in some way.

Is it going to be relevant like this, I don't know. For now, I don't think so, mostly because so far everything we've known about the Vex implies they are far older than anything else, especially the stuff we know about the Forge Star. The Vex are unfathomably old and the analysis about Volantis doesn't seem to be in any way incorrect. The Vex were one of the first living beings in the universe, inhabiting one of the first stars. As of now, I don't think there's a reason to doubt that, though obviously there could be new information in the future.

Obviously when there's shenanigans with time, so you could feasibly make a link in any way you want, but it doesn't feel that way to me, mostly because in that case, the Qugu would have it too.

The Qugu, however, knew of Darkness, and were using its psychic/consciousness aspects normally as a part of their civilisation. This comes from the Veil and that neatly makes the link between Maya (who is presumed to be the Conductor unless some incredible plot twist happens) and them and the Vex. It's also important to note that so far we've repeatedly had some strange connection between the Veil and Vex-based prediction technology (like the OXA and FWC Device), reiterated in TFS as well. As Ghost says, we don't know what the connection is here, but it's likely there's something going on.

For comparison, Psions also have the ability to share consciousness and speak psychically and share in "metaconcerts" that join minds of many individuals, even those that don't have psionic abilities. As in, this isn't just a Vex thing; rather it seems to be a Darkness thing. The Vex are also a little bit different in that they're just a species that functions this way, rather than being a species utilising a specific ability.

But again, any of that could possibly change going forward, and the further expansion on the Qugu lore is incredibly fascinating and begs the question: why were we given this information now? I think there will be something connecting the current plot to them and there's always a chance of some big new reveal, but for now I wouldn't overthink it too much in that direction.