Any tips for reaching problem-solution fit?

Keep your ego in check and don't fall in love with your solution. Always be willing to adapt and change based on what your users are telling you.

Keep on testing, pivoting, testing, pivoting, ... until you start to generate interest. Then you have to assess the business opportunities in that market (size, sources of revenue, costs, risks, etc.) to decide whether it's worth pursuing. It's not easy.