It is a template created with React Native and Expo (expo.io) you can create your App for iOS and Android that allows programmers to integrate their backend into any technology and add the necessary functionality to have a complete application of challenges, with multiple questions, individual challenges, team challenges, statistics, leaderboard, history of challenges that are the main screens that the application contains.
Example of real world customization and integration backend in Spring Boot (This is a succesful implementation of this template)
RetoGuru an Programming Languages Quizzes
Play Store, clic here
Apple Store, clic here