SEO and ads are useless. It's all relationship based. VC is just one example of how to build relationships. Ideally it's based on your network, and if you have no network in the area that you're building, question why you are building in that area.
That said, there are often startup incubator type organizations that will have companies approach them looking for innovative startups. Usually on very bad terms though.
Better, do some networking and find companies that have people who scout startups with new technologies, they exist.
If you're talking about building AI models for companies, that's consulting, it's not a product, and it will require even deeper relationships as you will have to explain to the company why they would want to do it in the first place and have them listen. (I have done this, it's entirely relationship based)