The key is to remember that you're an Outsider, an unknown quantity, and so you present an inherent risk from the outset (especially in the genAI field, which brings a lot of additional suspicion all on its own). What you need is an advocate who is already established and respected in the industry you're targeting. That gives you a bit of "social proof".

You have one customer... assuming that they are happy with your offerings, perhaps you can get them to be your advocate? Offer them a great deal in exchange for being able to use their name in marketing materials, to get them to write up an article about your product in a trade journal, to talk you up at trade shows, etc.

With good word of mouth, one customer becomes ten.