I've read recently about the pre-Islamic phase of Somali history, particularly in writing the language; (here's an example in relation to this topic) since it's actually part of an ongoing series of ATL stop signage across Africa, I've decided to use the Old South Arabian alphabet as ATL Somali writing system, and with a surprising twist: in this scenario, Somali is written in this script, an abjad, from left to right. In addition, the Somali territory in this scenario is a bit larger as it incorporated the Ogaden region.
The design of the alternate Somali flag is actually a variation of what you've seen in robo-diglet's Uncolonized Africa: Flags (Sultanate of Somalia, more specifically). Both designs combined the elements of OTL Somali flag and the flag of the Ajuran Sultanate.
Created and edited on MS Paint and Photoscape.