What happens to them after they leave Cybertron is told in the Exodus
I believe that WAS the original intention but the Exodus novel starts with Optimus in the archives, befriending megatron, working its way up to the major conflict, Megatron disposing of the previous Prime who IS NOT Zeta Prime as in War for Cybertron, then Optimus being named the new Prime by the council with Megatron present, which finalizes the segregation between Optimus and Megatron. They then go through the same ordeal of leaving Cybertron and go Planet hopping in Exiles.
I probably missed some important differentiating details between the books and video games but there is enough to make them separate but similiar continuities.
It's always hard to fit all these continuities together without ignoring small details like how Prime could be what happens after FoC but the fact that all the robots already knew about dark energon before getting to earth and rediscovering it. I guess they could have "forgotten" somehow.
Or how WfC and FoC could be a G1 continuity but there is the ongoing detail about the dinobots and combaticons.
It's fun always trying to piece these together. I wonder if they will make one more game that is on earth, or if they made a new MMORPG so the fans could kind of write the new continuity their selves.