I think you'd need stronger the Imazighen peoples (berbers) as a whole, sedentary and nomadic, or maybe give them more longer lasting leverage over Carthage as it grows. Might have helped them get better relations with the nomadic tribes who would have been more likely to spread some of their influence into the southern regions. More integrative processes and relations would have helped too.
I think it would have made the nomadic tribes more open to a more heavier and consistent trade with the Garamantes and Mauretanians. And from them maybe the Nok will pickup a few things and the influence will swing back from these native peoples as they steer Carthage or diversify some of its interests from being as eastern and Mediterranean oriented as it was. Mediterranean world would still be very important, but wouldn't be as much of a backbone as it was OTL.
Quick interesting thing I'd like to point out.
If you search for Akan gold weights, you'll find many of the symbols on the gold sets that match up with the current tiffinagh script. Now many of these gold weights were made a few centuries ago, but the fact that the symbols used are more than vaguely recognizable with this current north african script and the fact that many times the so called weights were used to store information seems more than a coincidence. This seems to suggest that there may already have been an avenue for ancient contact of northern africa with subsaharan africa through their writing scripts, or at least a distant proto-culture.
Keep in mind that many of the groups present in what we now know as sub-saharan africa also migrated from more northernly locations too, like the hausa, fulani, some akan groups and other groups near the chad basin. Maybe this area could become more of an incubator for a saharan trade script or traders language thanks to the garamantes? The garamantes, were found to have a wide trading network, so the possibility of groups within the area exchanging, learning and teaching with their northern counterparts might be a thing if Carthage can establish more friendly relations with their neighbors in the interior.
If not that maybe have sedentary Imazighen interfere more in Carthaganian politics or use their brethren and their contacts as counterweights for more leverage over Carthage.