@metalinvader665 You raise lots of good points. In regards to the ivory trade, I assume Greenland might still be able to be profitable for the ivory trade as the ivory from Africa would be travelling vast distances and thus I presume to still be quite costly.
Walrus ivory is produced in smaller amounts (never was a lot of Greenlanders) and has to cross the stormy North Atlantic. Elephant ivory does have to cross the Sahara, but there's precendent for that trade which will increase since camels will become widespread in North Africa thanks to the Arabs. To export to Britain or Scandinavia, a ship only needs to hug the coast. The economics are much worse than the advantage walrus ivory had OTL.
In regards to Morocco, I think a powerful king could easily shift the attention from land to the sea as Morocco is an easily defensible position so they could decide to not focus on expansion within the Maghreb, however, I do find this unlikely.
Perhaps, but at sea there's the issue of the Canaries. As Mauretania develops, it's likely the Canaries are brought into the range of African civilisation earlier than OTL. They could be a lot like Ireland, and subsist on piracy of the Mauretanian coast. They're an obvious target for expansion, basically Mauretania's "Ireland" so to speak. But yes, there's the obvious dichotomy between choosing to support land expansion--east toward Numidia or south toward the Niger--or sea expansion--the Canaries, the Atlantic, Africa, etc. The sea has less geopolitical implications, since the Iberians are less likely to care about invading the Canaries than an attack on Numidia. Or an attack on Iberia, since controlling the Straits by ruling Baetica (separated by mountain ranges from the rest of Iberia) would be a goal of a powerful Mauretanian king.
I should add there's the ever-present issue of the Berber clans and confederations of the mountains, which is a topic worth noting in any discussion of an alt-North Africa. I've made a comparison between Christian Mauretania's issues with these Berbers and the clans of the Scottish Highlands and their impact there, and the Cossacks in Poland-Lithuania and Russia are also a relevant example. These Berbers live at the fringe of society and represent a source of support--or opposition--to the ruling class in the lowlands along the coast (who control the key agricultural lands as well as access to foreign trade). OTL, there was the
makhzen ("warehouse") which was the elite of society--including clan chiefs and their followers--bought off by the rulers of Morocco, and the
siba, anarchic mountain/desert regions governed by local communities on the basis of religion. These communities would accept the spiritual authority of the Moroccan sultan, but their main spiritual influence was local saints, and they would not accept the control of the
makhzen (although if the right deal existed they might). I think there's an obvious basis for an alternate version of this system in Christian Mauretania (note that a similar system is found elsewhere in the Maghreb OTL)--even OTL the roots of this system can be found in how Carthage and the Romans dealt with the Berbers.
That will likely be how internal politics in not just Mauretania, but "Numidia" (centered around Icosium/Algiers or Cherchell/Caesarea) and "Africa" (centered around Carthage) and any other North African state will evolve. Africa has the easiest route to weakening this system--the Archbishop of Carthage has such religious influence and the coast is so rich and populous that its ruler can suppress the anarchic fringes and centralise. Now, we don't know how North Africa would evolve--I can't think of any European equivalent of rich port cities and tribal hinterlands, and we should remember that OTL Morocco will be an utter fringe for a few centuries until Christianisation and full integration into the region takes hold, and I can't help but think linguistic/cultural differences (the northern extremity near Tingis and Lixus will speak a Romance language akin to that of Baetica across the Straits, unlike the Berber speakers of the Rif and southern parts) will play a part in how the country evolves in relation to the rest of the area.