Sounds like Godsmen propaganda tbh. The Outlands is the lynchpin, and Sigil a representative of that. There's no indication that Pandorym is interested in anything beyond a single crystal sphere and/or the gods therein, much less the entire material plane. There's no indication that if you kill the gods anything bad happens to the multiverse as a whole, or that removing the prime material plane won't cause a new one to be made from the intersection of the Astral and Ethereal.
In Grand History of the Realms, a 4e book, the timeline of Faerun include Pandorym awake and chewing up the countryside for four years (1370-1374) without... really killing any gods or destroying the multiverse as it stands? And then he's put back to sleep by a couple of high level adventurers.
From a deific perspective, that's... really not all that impressive?
I mean, by posing the question in this particular thread, you tacitly acknowledge that you are asking for afroakuma's perspective and that his answers are definitive. This is afroakuma's Planar And Other Oddities Questions Thread of 8 years running.