In Su Ming's view, in the DC Universe, the source of all "evil" was actually God. Lucifer was merely a son pushed out to take the blame, and since he did have some issues himself, the title of evil in this world had been pinned on Satan's head.
Think about it: if God was omniscient and omnipotent, how could Lucifer have succeeded in doing evil if God had not allowed it?
At the very least, it was tacit approval.
In short, Lucifer could exist in any story universe with myths of Heaven and Hell. His fall was even famously renowned, giving him plenty of prestige.
Because in story universes with that system, God was often the supreme deity, making Lucifer second in rank. His power came from the stories of the Bible and people's desires. He could not merely use External Force; he cultivated both inside and out.
The Hand of the Void, meanwhile, was evil from the "outside," an evil belonging to the Narrative Layer.
For example, in his previous life, when Su Ming read stories from the DC Universe and came across something disgusting—like Warner making another godawful DC Superhero movie—he would curse, "Warner Dead Horse," then carry on with his life as usual.
It seemed like a trivial matter, but the malicious thought that arose while cursing, the wish for all Warner executives to drop dead, now also formed part of the Hand of the Void's power.
The more DC haters there were outside the Fourth Wall, the stronger the Hand of the Void became. Its ultimate goal was to make the DC Universe vanish completely and return to nothingness.
Put plainly, it was the sentiment of, "Trash company, go bankrupt already."
Its form of existence was somewhat similar to Mandrakk, who represented the "editor-in-chief of DC