A really good PoD is if Ethiopia signs a peace Treaty with its Somali neighbors Adal & Ajuuraan where they cease fighting and become allies with a mutual defense agreement. Once the peace treaty is finalised, they'll fight the oromo hordes together and push them all the way down to Mout Kenya. Then, Adal and it's souther Somali neighnour, Ajuuraan, would unify to form a unified Somali state called "the Samaale Sultanate".
After Samaale and Ethiopia are done cleaning up the Oromo mess they'd each annex a portion of Madri Bahri, as well as the Afar and Oromo territories that separate their kingdoms. Afterwards, once they're done consolidating their newly acquired territories and people, they'll spend the next few decades expanding into the neighbouring countries/territories of Oman, Ottoman Egypt (the Sudanese portion of it), Yemen and the Swahili City States. The Somali of course will have a much easier time assimilating the newly conquered nations because of Islam and the fact that they have already been assimilating Arabs and Swahilis for centuries.
That's all I can think of right now.