I think it really depends on your category. I am kind of in the same boat trying to promote my app, and I did follow the advice of making a MVP and trying to get feedback before moving on. But even after doing that I am struggling to reach the right audience without a marketing budget

I also have heard that trying to sell something before making it can tell you if it has real demand. People will tell you something is a good idea and not use it themselves all day long, but they will not pay you even a discounted price for it if they will not use it most of the time. Here is a link to the podcast episode: https://www.youtube.com/watch?v=Ec9K6ZV3Ds4

Validating a b2c startup can be tricky! I've been there. Have you checked out BznsBuilder? It's got great tools for business planning & financial projections to help validate ideas before building. Might save you time & headaches