Finding customers to interview / first customers (I will not promote)

I am currently working on a project on the side that I think has some broad applicability for FP&A departments, but not sure how to fully validate this outside of some prior industry knowledge I had. I didn’t work in FP&A specifically, but was a consultant and worked with many FP&A managers in the past. And while working with their models I continued feeling a pain point that I’m trying to now solve. This is very much a side project that I had a random burst of inspiration for, so I’m not sure if I want to