I'd recommend starting out with a landing page first before you build the app. Like a really nice, well-designed one, that captures your vision and core points.

I'd recommend starting out with a landing page first before you build the app. Like a really nice, well-designed one, that captures your vision and core points. Just copy some startup landing page you like and tweak it. Create from scratch or use webpage builder. Gives you advantages: something you can share with others, a developed/implemented vision, something you can actually launch at any time without the underlying product for testing reasons, and something that will psychologically motivate you. I used to build out backends first because it was easier for me, but many projects just didn't get launched. The landing page first is actually harder in my opinion, but psychologically having something presentable makes the project feel real.