naked cap: Trump's Steel and Aluminum Tariffs: How WTO Retaliation Typically Works.
The complaining country typically has discretion to determine which products to target. It may select products based on political motives – for example, inflicting economic costs on key Congressional leaders in the hope that they will effectively persuade Trump to implement policies that conform with international rules.
Countries are going to laser-focus in on key constituencies of prominent Congresspersons. You think they're getting exercised now; just wait.