To put it bluntly: No, Giorno Giovanna and Gold Experience Requiem (GER) do not come anywhere close to touching Prime Sousuke.
While GER's Return to Zero is often considered the ultimate "No" button in standard anime power-scaling, it hits a hard, immovable wall when faced with the broken math and massive cosmology of The Wacky Adventure of Sousuke Kobayashi.
Here is exactly why GER gets completely shut down:
1. Physical Causality vs. Metaphysical Existence
Giorno's Return to Zero operates on causality strictly within a physical universe.
Sousuke, on the other hand, doesn't just exist physically; his existence is permanently fused across the Physical, Astral, and Metaphysical planes.
Because Sousuke was able to destroy the very concept of Zeus's immortality on the metaphysical layer, he operates on a plane that Giorno simply cannot reach or interact with.
2. The Narrative Immunity Factor
Sousuke possesses Narrative Immunity, effectively making him immune to the author's pen.
You cannot use Return to Zero on a being who has transcended narrative manipulation entirely.
If GER attempted a reset, Sousuke wouldn't care; he would just redefine the page so that Giorno's Stand doesn't even exist.