Ecommero is made using some core libraries for handling navigation React Navigation is used for making layouts only flex is used. It is built using Expo.
React Native is built by Facebook. It's relatively easy to write cross platform apps. If you are from web background with some familiarity with React it will be much easier to use React Native because React Native uses React.
React Navigation is used for routing and navigation in React Native apps. Navigator has some common elements which Ecommero uses.
Drawer Navigator Its used to make a drawer when a user swipes from left to right or presses the drawer icon
Stack Navigator Stack Navigator stacks screens on top of each other and only one screen is shown at a time
Switch Navigator Switch Navigator is used for the authentication flow inside application. Currently no authentication happens in Ecommero but for good practice all routing related to authentication is made using this
Expo is used to make react native applications. It provides a set of tools that simplify the development and testing of React Native app and arms you with the components of users interface and services that are usually available in third-party native React Native components. With Expo you can find all of them in Expo SDK.