At what point of recommending a competitor is worth it than building from scratch? [I will not promote]

I was speaking to a lawyer friend who is helping me deal with some basic legal requirements. (Nothing serious, done everyday, not important). They lay out some issue they had that they are extremely annoyed about and mentioned alot of lawyers deal with this. As a fulltime SWE, I immediately thought of a solution and would love to make it happen in hopes of a deal. The thing is, im now stopping myself to think: I s it worth trying to create a specific product to solve a specific problem or just find a competitor or large company to recommend? Creating the product is easy, finding the customer base is not. My first job is at a startup and I was there before they had their first customer. I see the hard cold calling they did and know the pain. The friend said the most they can do is let the office become the "test office" but nothing more beyond that, which only provides little help in terms of how its being used but thats it. The most I can do is a basic MVP. If they like it, it would be something small to maintain and if they see a huge value in it, I need them on board since im not familiar with the field and do not want to sink hours to fully understand if i am taking it on alone. What do you think about this?