Inititaly I thought this was an easy problem, but I just can’t figure it out.
Here is a simplified example. I have 8 different people buying some items from a store. Afterwards I want to look at all the items and sort them into groups so that each overlapping initial shopping goes into the same new group.

input would look like this:

| person |             items |
| ------ | ----------------- |
|       1|             [B, A]|
|       2|             [C, A]|
|       3|          [E, I, D]|
|       4|             [F, G]|
|       5|                [F]|
|       6|             [F, H]|
|       7|             [J, A]|
|       8|             [K, J]|

and output should look like this:

| bag |          items |
| ----| -------------- |
|    1| [A, B, C, J, K]|
|    2|       [E, I, D]|
|    3|       [F, G, H]|

I tried crossJoin, array_intersect, concating arrays and also doing all this in several loops. But while it eventually leads to bag 1 ([A, B, C, J, K]), I cannot easily identify the smaller bags and at what point the group is complete. Am I overthinking this?