In DynamicAction, can you see what other customers are buying within a promotion?

Yes, you can view layered data within Dimensions. You can select a customer segment and then pivot to another dimension, such as promotions and then pivot to product category or product name. Lean more about layered analysis functionality.

You can also see customer basket analysis to understand what combinations of categories and products are frequently purchased together within a promotion or understand promotion stacking. Learn more about promotions and basket analysis.