Even when there is wobbling of axes of the orbits of the man-made satellites, the earth’s center of gravity is expected to remain constant for the co-ordinates reporting, using WGS84!

I Go from a premise that the earth’s center of Gravity is fixed and coded (0,0,0) in a Cartesian graghing system.

Besides, all the satellites in the orbits are not powered, instead they are held in their orbits by a centripetal force.

So, how then do we start talking of an error of 2 cm?

Is there any earth orbiting satellite, whose orbit has a center not coded (0,0,0) according to the Cartesian graghing system for a three dimensional analysis?

The best way to improve positioning integrity in Africa (and many other areas) is for countries to try and invest at least a single CORS (Continuously Operating Reference Station) into the global GNSS network — https://igs.org/. That would contribute to increased capability of processing GNSS positions with online utilities such as the US On Line Positioning User Service (OPUS) or the Australian AUSPOS which can provide cm-level results with sufficient observations from dual frequency receivers anywhere in the world.