Form a team of 2 to 3 people.
Build a chat app, incorporate Redux for state management.
An example is provided for you in src/App.js however it does not use Redux and is lacking a message viewer.
Note: Your message listener callback hear() will not be fired for messages you send, only messages from others.
Note: Everyone is in the same channel
Note: No there's no security
Note: Yes you can steal someone elses nickname... have fun!
If you want to go crazy take the connection object and have a look at SendBird's docs. The connection object is effectively sb.