Interesting find here: https://logcluster.org/sites/default/files/maps/Map DRC General.pdf
Not sure if this has been posted here, apologies if it has. There's actually a little port to the west of Manono at Myumba
Myumba close up, doesn't look like much development.
Map legend - picture of little boat - "secondary port". The blue line represents a "navigable stream". All the way down to Bukama
Bukama railway leading south - port.