so uh No, there are no other gooeys from other universes.
No gooey by himself is not god.

leme explain, *breaths in*

In gooey's world there used to be an evil entity/god who reigned for thousands of years but was cut in 2 by a sorcerer and was never seen again. Gooey and Citrine were those two halves and if they ever combine the apocalypse will happen.
also
3rr0r_G003y's deal is that its an alien ai gone wrong that that landed on Gooeys world and took the form of gooey.