Harrison is already a serviceable point guard if you going to bring things down to that level. But if you're talking about a player developing into something remotely comparable to Harrison as a defender, it basically never happens.
I haven't seen signs of especially good court vision from Okobo or Harrison and it's unlikely they'll develop it, IMO. But they can both make the simple pass and don't attempt passes
that are beyond their skill level. Like I mentioned we haven't seen Igor's 'motion' offense but if it's anything like I'm expecting, it won't require exquisite passing skills - after all, the whole team is expected to make the required passes. That should be a piece of cake for either of them.
They will run the pick and roll - the national team that Igor coached did that - and they are not going to run that great. For the national team Doncic was the ballhandler in the P&R, and he was very good at it. He's going to have lower his sights with this team because we have no one that passes as well as Doncic did. I'd expect Okobo to have the most experience at it and probably be the best of our current players - he's not a great passer but he doesn't get rattled and he can shoot if they give him room. Harrison will drive off it, like we saw him doing in SL, but he scored at a decent rate - and we'll be giving them different looks.
They will also feed Ayton in the post. Now feeding into the post in general is challenging but Ayton is a very large target or he will be when he learns to give himself a wide base and seal his man better. Harrison in particular tried to make the entry pass when he shouldn't have and it did fail in those cases. He does have to learn when to abort the play because the pass isn't there and he has to work on the timing of the pass to get it into a narrow window. It's not something like learning floor vision - it's a simple pass as long as he gets the timing right. Ayton can help by moving toward the pass, too, when he hasn't sealed his defender.
I'm not saying you're necessarily wrong, but I do think you're putting a LOT of stock in summer league, which is basically a glorified practice and one where the majority of the players will never play in a meaningful NBA game. We're talking about a guy who didn't even start much in the G-League last year, who is a poor outside shooter and who doesn't even have a guaranteed contract. I cannot say with any certainty that Harrison or Okobo are good at
anything at the NBA level, but I think, especially early, they're going to struggle mightily as playmakers. Harrison didn't just struggle with entry passes, there were several plays every game where they ran a pick and he didn't even seem aware of how the defense played it other than the man in front of him.
I expect no matter who is the point guard, when we're in half court sets, Booker will be handling the ball a lot and most pick and rolls will be ran through he and Ayton. Which is fine. And like I said, if we're unable to find a multidimensional PG, I'd rather stick with Harrison.
I do expect Harrison will get a chance to prove himself this year. Okobo on the other hand... I think it's going to take some injuries for him to see much of the court, after a nice few shifts in the opener he crashed back down to earth. I like the pick, high upside, but I think he's a ways away from being ready. Unless Knight gets hurt then Okobo will probably play more in the G League than here next year.