I haven't spent much time in the philanthropy world, but I've worked with a lot of digital product startups to help them refine their pitches and raise millions of dollars in funding, ranging from seed stage late-stage startups.
It sounds like you have two separate, but related, questions here:
1. How to make money from a free directory site
2. What you need in order to raise money to build the site
For the first question, there are many ways to monetize a free-to-use digital product. You can charge for advertising slots on the platform, collect and sell user data, set up affiliate links for revenue sharing, use a freemium model... really the options are endless. It ultimately depends on your target user.
For the second question, the answer is really that it depends. It could be, but looking at what you're written, I'm unclear on what your differentiator is. Why will people use your site as opposed to another one? Is it simply that you would be the biggest after having built the site? Why should investors go with you as opposed to another entrepreneur? What's your plan to attract traffic and users?
From just what you've written here, I don't think this is enough to raise money – but if you've got a more thorough plan or you have some other differentiator or key advantage things could look different.
Feel free to reach out if you'd like to set up a call to discuss this further. Either way, wishing you luck!