Yeah all we can do is be hopeful that the mansucritps survived. I suspected more survived than we might think. I'd put it maybe 10-16000 manuscripts. Since yemen has around 50,000 manuscriptsNo on the contrary, it was the same with the collapse of of other states/civilizations for example the Roman Empire, much of the writings and texts disappeared along with the ruins.
It really is a shame, Zayla was referred to as being a manuscript production place, that distributed books and Mogadishu was described as a place of ''high arts and sciences'' and had many schools.
There are not that many swahili manuscripts tbh, most of the ones i have seen available online are just a handful from the 19th century from mosques. We have similar private collections from Mogadishu, Merca and other areas of Somalia.
Hopefully there are murid/faqih families out there have preserved some of it. And perhaps we will get some epigraphic writings written on monuments, tombs and graves to learn more.
Regarding your point about swahili manuscripts. Yeah those guys don't have any mansucripts before the 1800s. I think maybe a couple from the late 1700s. Same with west africa. I read the paper on how the hundreds of thosuand of manuscripts is really 1 or 2 sheets being called a manuscript. On top of a lot of them being from the 20th century with a few 19th century and nothing yet from the 1600s golden timbuktu period. You can even see this with how they only have 2 chronicles people constantly use with both being from the late 1600s. I tried to find something else but nothing came up with is strange considering how the mali empire and timbuktu is described. It's made me realize somali arabic manuscripts are the oldest in all of subsharan africa. We likely even have some from 9th or 10th century that survived.