This is just a passing idea of mine. I can’t make mods myself, so I make this topic just to pour my ideas out.
This is my simple idea of a Byzantine civ mod (I know it’s too far fetched in AoE 3 timeline), my suggestion is that some of the units in the game mostly Chinese units could act as a base to make the Byzantines units.
Byzantine Armies AD 1118-1461 (Ian Heath, Angus McBride)
That’s it I guess, if I find more ideas, I might update this topic from time to time.