Another young and inefficient player to compare him to would be Jonathan Kuminga, who struggled as an 18 y.o. with GLI. GG has shown more shooting and self-creation flashes than Kuminga did. I think most people view GG as a high-upside prospect.
Maybe....I think we're still figuring out to evaluate GLeague players. I think that was the covid year right? Kuminga didn't fall very far and was much more of "toolsy" player than GG imo. Kuminga was one of the best athletes in the NBA the day he got drafted and he's making his way as a non shot creator. Even if he was struggling to score in the G-League, that was not his entire game like it is with GG. Maybe Jaden Hardy is the better reference point from the G-League as someone who truly lost a lot of draft stock.
I'm definitely away from the crowd as what I view as "potential". I personally just find that most of the guys who really pop later in the draft are not the traditional "high potential" types. For GG, I think that even if he figures out the shotmaking stuff he has a million other things to work on besides that to be a high end player. There's not really a star out there who is only a star because he can get buckets. They either have a much more complete offensive game that makes them truly elite or are much stronger on defense. I think he can be Tobias Harris, for example, but he will never be someone like Siakam who has a lot more to offer besides scoring.