Nah,
There are 4 types of Sudan
1) Old Sudani before it broke up, south sudan before it left sudan: straight up bantus/nilotes, dinka, tall, super dark, kneegrow
2) Admixture: these are mixed with what seems like the super dark ones who were given islam - some of them are a mixture of arab and those south black Sudanese, or they looked to me like that - these are muslims, more prominent black features, but different from the asli/original Nubians and the full black ones, they are basically black made muslims or who mixed with arabs and original nubians
3) arabs, or still very strong arab looking or at least 75% arab lack with a little distant mix of blood
4) the asli or original sudani, the people who ruled ancient egypt, the creators of Meroe, kush - they are the original sudani that blacks boast about- called Nubians, - they usually look very somali, like their somali cousins, usually tall, soft hair, finer features, thinner lips, nose etc
the ones who all look like the Nubians are to me just their cushtic cousins like beja and others from eriteria/sudan,
sometimes you will get a dark skinned Nubian and with little hard hair, but this is the same with ahmaara/habasha, you will get ones with little more kneegrow features, this is due to centuries of shagging with neighbours,
sure most average arab sudan is really a mixture of nubian and darker more bantu groups, but the average sudani looks somali and seem to be arabs mixed with nubian and more related groups like beja and of course more black featured groups
i could be wrong but that is my observation , correct me if i am mistaken,