The next step in the Lean Product Process is to define your product value proposition, which is the next layer on the Product-Market Fit Pyramid. At this point, you have identified several important customer needs that you could potentially address. Now you need to decide which ones your product will address. You want to do so deliberately and resist the temptation to tackle more needs than you should.
A good product is designed with focus on the set of needs that are important and that make sense to address together. Swiss Army knives are incredibly useful, providing a set of tools to address a wide range of needs all in one convenient package. But at some point, as you add more and more tools, a Swiss Army knife gets wider, heavier, less usable, and less valuable. Focus is critical when defining a new product.
You also don't want to unnecessarily risk wasting resources with an initial product scope that is too large. You do not yet have perfect information about all those customer needs. There is quite a bit of uncertainty in both your hypotheses and in what you think you know. That's why you want to start off by identifying the minimum viable product. Remember, all of your hypotheses about customer needs are hinged on an underlying assumption about your target customer. If you test your MVP and realize that your assumption was wrong, you will have to revisit your hypotheses about the relevant needs to address.
Even if user testing ...