I often thought it was named after a specific beasty.
From reading the wording in the fluff (both current and fifth ed), it comes across that way. Though both also say that only the name remains, not the idea or knowledge of what Quango looks like.
Reading the 4-6 result for using the item, it sounds like it's an incredibly powerful version of a Coatl, as the egg opening is followed by a boom of thunder and it smites the foe and then flies off. It kind of gives me the impression that Quango is to a Coatl, what a Dread saurian is to a cold one.
And all this from a hatchling a few seconds old, think about that for a moment....
Combine the North American thunderbird, crossed with the Aboriginal Rainbow Serpent, crossed with the Rok (Or "Roc" depending on the cultural reference) and you're probably close to the mark. It's something whose very presence, summons storms, annihilates entire armies and most likely could give even the old ones a run for their money in terms of power.