I guess than the void exist well before he who romains because when he explains about the multiverse war at loki and sylvie you saw his variants use the sticks for prunes the peoples

I feel like it is a dead universe battle royale type thing, yknow, based on its landscape

I am not really sure who

But a higher being was able to make it since the TVA is aware of it

It existed already. Alioth was harnessed, but already existed there. With locations crashing in from the TVA, but other than that, it's an endless void already in existence nearing the End of Time.

The void is most likely a phenomenon that naturally existed instead of being created. It's at the tip of the timeline always moving infront of time. If time was a train, you'd have to go to the front car an jump off an the dark tunnel ahead could be the void. ( at least through my lense )

Alioth however did not originate in the void. Alioth was a wild unknown until He Who Remains used it as a weapon which helped him win the multiversal war. After that the creature became both Gate Keeper of The Castle Fortress beyond the void , and soul eater within the void.