i actually think a folding bike is better at transporting grocery, due to the small wheel size.

my Dahon boardwalk with a large metal basket in the back can carry a ton of groceries.
and the lower enter of mass, due to small 20" wheel size, means the extra cargo does not effect handling.

my oma has big wheels, so the cargo is very high. you can feel it is no good.

Having a folding bike and a bike like miss grace or oma seems redundant to me.