How could he?

In the chapters where Sunny attained the [Shadow Weave], it was stated that he could, with effort, turn his essence into true Darkness.

We all know that Darkness is the enemy of shadows.

It was also stated that True Darkness was outside the Gods' jurisdiction and does not follow their ranks at all, and that it wasn't of the World but of the Void.

But then again, the Gods were also born of the Void, so there is definitely some relation between them and things of the Void.

My question is: what could be the process by which he could turn his essence into True Darkness?

It has to be fundamentally different from what he channels Neph's or Saint's Essence to copy their abilities or physicality.

What do you think he would have to do?