[fjabre]

Good points.

One other pitfall I see is that initially, you want to market the idea to some targeted audience. That audience may or may not be HN. I don't believe a true product-market fit will be evident simply by 'validating' an idea on HN/PH. A true product-market fit should only be evident when directly targeting the audience the app was designed for. And the only two experts in those domains will be yourself and the customer.