My father has been a wholesale distributor managing 400+ shops in Mumbai for the last 30 odd years. I have traveled with him too at time for his visits.
The most critical thing that I have noticed that helps you to reach out to shopkeepers in the distributor network. Their relationships with them are the strongest in the supply chain and they consider their distributor as their eyes and ears to what is abuzz and trending in a particular category/about a particular product.
Although loyalty programs and incentive schemes work in certain categories. Most shopkeepers are looking for a good quality product that will get picked off the shelf as soon as possible.