Leverage Google search data! There are tools such that allow you to see how many people are interested in certain products/categories and how competitive those areas are within SEO. Although it may seem like a narrow view; how people search, the volume at which they search, and what they're searching for can be a great way to identify niche opportunities that are under-served today.

As someone who leads growth marketing at a large e-commerce, I'm constantly looking for new product opportunities that can create value and solve gaps for consumers today. Feel free to schedule a call and I can walk you through how I've found success doing so.