Ireland played a interesting contribution to world war one. Both sides in Ireland both fought and died together in the trenches, Irish nationalists and unionist battalions fought together against the Germans. The two famous battalions of old Ireland were the 36th Ulster division and 16th Irish division.
The 36th was a unionist battalion.
While the 16th was nationalist homerule supporters.
But tbh I just think seeing Irish troops in a ww1 game would be cool since they don't appear as much in these games.
I think for what to add is Irish accent maybe. A Dublin accent and then a Ulster accent.
Meanwhile for cosmetics I think it'd be nice to get a custom helmet paint that soldiers in the 36th sometimes painted on.
But sadly I think that's the end of cosmetics as unlike Scottish troop Irish soldiers wore mostly the standard khaki uniform.
Image is a example of what I mean by helmet paint job