I think that Ball could be okay in Philly but probably for different reasons than you. Primarily he could throw into Embiid then cut and not be under so much obligation to create in the half-court. Also Embiid requiring a double team could enable Ball to spot up for the 3. But more importantly Embiid being behind will help Ball to cover for his defensive deficiencies.
The Lakers are a poor fit to the extent their defense is garbage and guys behind him are not going to cover for him when he gets repeatedly burned.

But Lonzo would have scorers to his left and to his right with Clarkson, Russell, Ingram and Randle. He was a low usage player at UCLA and would be allowed to assume this role. So I don't know how this makes for "decent to poor fit."
In Philly, you would have a backcourt with two guys who need the ball to maximize their skill set. If Simmons is leading the break, that doesn't help Ball any. And if Ball is leading the break, he is not going to have Simmons as a spot-up shooter. I don't know if I see a Simmons and Ball backcourt as all that compatible. They will be terrible defensively against smaller guards. I don't know. Simmons needs a guy like Monk next to him. A pure PG like Ball does NOT seem like an ideal fit next to Simmons.
The bottom line IMHO is when you have a flawed player like Lonzo Ball there is NO optimal destination because he is going to exposed wherever he goes.