Somaliweyn as a whole were historically not an oral society any more than most societies were. The ottomans literacy was only 5%, in India and Middle East were the same too. In most of Europe the literacy rates were abysmal and only exploded after the Industrial Revolution. Tbh the places that had any significant literary tradition in Somaliweyn would be the coastal towns and cities, sedentary farming/settled regions like Hararghe, the south, and old islamic areas in the North.
Many foreign scholars like Lewis couldn't get their hands on Somali manuscripts kept in private libraries (because they didn't trust him most likely) in the 1900s so he quit and parroted the whole “oral society” bullshit and everyone else has been singing it since.
Truth is, every major clan and sub clan, each major city and town had learned men that kept a record of lineages, the important saints, trade agreements, poetry, treaties and historic events. Cassanelli for example during his research on the medieval South was well aware that the various old towns and cities he visited had sheikhs and learned men who had manuscripts in their possession detailing their history but he failed to access them because of a lack of trust with them.
Once Somalia is at peace and research is done in the country, it’ll be possible to undo these old academic stereotypes and gross generalisations placed on the people and country.