Struggling to get customers for 1 year

Title explains it all. Over a year ago I created MealManifest: a mobile app for recipes that I want to sell as a white-label app. I launched a landing page and started to get good sign up rates for demo with Google ads or just organic. For example without any ads, once a week I get a demo request via form. Most of those requests never reply back to my email when I offer a call to do the demo. Even after doing demos and it seems people like the app, I haven't got any sale 😞. I got around 70 demo requests and done 10 demos.

They usually don't say any reason why not, but sometimes mention that I don't have any clients published yet.

I'm not sure what to do at this point… Just a chicken and egg problem, I suppose. To make a sale, I need a sale…

Any advice from the community? Maybe someone had similar experience and found a way out?