That would work in FTM as I believe you can insert a photo for each person. That photo would be the country flag.
My goal was a simpler. In recent weeks I have assisted nieces and nephews with class projects. For children their age it would be nice to give them the fan chart supper imposed over the world map and have some connection to the country of each person's birth. The map would be less abstract than the flag. and would quickly show them the world distribution of their ancestors.