Some nice examples on Indie Hackers of people who found creative ways to gauge demand for a product before fully building it.
The classic example is using paid ads to drive traffic to an email capture, with an instruction like…
To start your order simply fill in your email below.
You then measure how many visitors sign up, and tell those who do that you will be in touch once you’re ready to accept new orders 😎
To take this a step further, you can see how many people are willing to pay upfront for the product, offering a discounted price for preorders. If you don’t end up building the thing, you can simply refund everyone.
Another smart approach to product validation: Riskiest Assumption Testing