My experience is that even if you find a business owner with a problem there's a steep climb to build a product and sell it. I'm a developer & my brother is a mortgage broker - I even worked for a few months in his office during the sub-prime bubble :-) I saw first hand many processes that could be improved , even coded a few hack "solutions." In my case, it was just too easy to get a high paying dev job than take on the risks and costs of starting a business. Coincidentally, a recent indiehackers podcast with Dave Sims of Floify (a mortgage broker product) validated what was needed. I recommend listening to this episode - very good info developing a successful product for a domain you don't know:

https://www.indiehackers.com/podcast/136-dave-sims-of-floify