Build for existing audience
Build new products and features for the audience you already have - not the audience you hope to attract. It's important to get feedback early and develop a sounding board for ideas. Products and features should be built with the customer/client/user in mind, and it's much easier with real access & feedback.
At some point, the product will need to be introduced to the target market. It's best to prove that can be done early by finding your target market within your existing audience and asking for help. It'll be easier to understand perspectives and learn if the existing audience cares.
The audience doesn't need to be large. Identify the people in your audience with the problems your product solves, then reach out. When it's real problem and there's a pre-existing relationship, it shouldn't be difficult to find those willing to listen and invest some time, in hopes of a solution.
Get the product to a point that your audience can understand it, then seek feedback to help mold the future development of the product. Iterative progress can feel slow - and will help prevent wasted time and resources later.