How do I get the first few customers?

You could reach out to your target audience on social media. There are thousands of people across different networks who ask "can anyone recommend...?" or "where can I buy...?" daily and a majority of those questions remain unanswered. Combining your most relevant keywords with those phrases could help you find some potential customers. Other than that, you might find some inspiration in this video https://www.youtube.com/watch?v=1H6QejI3rLg&t=127s

You can get feedback from your product through betalist for some objective users, but this might not be your target audience for your product.

It's easy to go viral!

Syften provides you with filters more advanced than the alternatives, which allows you to monitor your niche in details. It helps you find people on the internet with an itch that only your product can scratch.