as of now you are right, there is no single leader who controls all of somalia and siad barre AUN was the last true president. if we look at waqooyi you have huge parts of sool and sanaag which are not controlled by siilaanyo,
and faroole does not even control parts of mudug and bari.
the somali government does not control a single town. and kenya only controls kismaayo, 5 min outside of kismaayo you have hiiraale on one side and al shabaab on the other.
but all this can change in time but what cannot change is the sovereignty of somalia.
You mean recognized sovereignty because right now there is no sovreingty in Somalia , Somalia sovreingty can be breached by Ethiopia Kenya any time they want there is no sovreingty although the UN recognized Somalia's sovreingty they cannot protect Somalias sovreingty from being intruded. Sovereignty is protected by the actual country the goverment and the security forces. For example Somaliland has sovereign control over its territory ,although the UN does not recognize that. The regional countries recognize that informally perhaps but they respect the boundaries , except Somalia but they are toothless.
Siilaanyo controls more than 93% of the former British somaliland in territory only parts of the taleex districts is out of his control and parts of dhahar district. The rest is under his control, and the southern part of the buhoodle district. The rest of the country is under his control
Faroole controls all of bari only a few mountains not he controls all the daarood districts of mudug we can say 99% of bari nugaal and northern mudug is under his control. Jubbaland controls controls Kismayo with the help of Kenya and some districts afmadow and others dhooblay and since a few days they moved into goobweyn but they used Kenyan logistics and military support. The same way culusow does with the ugandans and the Burundians and the Ethiopians.