How do I display an array (list) with array (list)?

Hi, I'm currently using local data, ie, by creating a data type, and then setting an app state.

The data type is is a list of dataStruct, and within each item of the dataStruct, there is another list containing another datastruct.

My question is, using itemList (or anything else if you'd like to suggest), how do I display something like by generating children from a variable?

index[i].data from i
-- index[i].index[j].data

Hope that makes sense.