App Development (Android+iOS)+Design

We are looking for a app developer who can suggest design and develop app from scratch. We will provide all requisite info and best possible look of an app but developer needs to suggest theme, font, color and navigation etc. Data compilation from few websites. we will provide an example (Most important feature). We have logo, splash screen and icon ready. Suggestions are welcome. Project deadline is 15-20 days (negotiable). Interface should be great (will provide few apps as an example). Money will be deposited with upwork and will be released in two phases, once after testing the app in our mobile and second after publishing the app. We have developer play store account and will publish app under our credentials.