Start with the customer and the commercial decision
A brand exploring US acquisition can be offered several channels before it has a usable traffic brief. I begin with the product the team wants to grow, the customer use case and the reason an external message could help. We establish what customers should understand before they click and what the Amazon destination must confirm.
This creates a smaller, more useful test. The Irish team can agree the creative, approval owner and spending boundary without assuming a full multi-channel launch is required. Available measurement is defined before activation, with source-platform behavior and Amazon reporting retained as separate evidence for the decision.