Along with following a React course, I created a simple React app to get used and learn React fundamentals:Props, State, Components, Create React App, JSX, TypeProps, Events handling, Lifecycle are some of the concepts I've became accustomed to. I also developed Auth methods (Facebook, Github, Twitter) and made use of Firebase and localStorage.
It has been developed mainly without using Hooks, I've used class components to learn the basics.
See it live --> HERE. Just enter a random store's name (or leave the default one) and click on Visit Store; then just sign in a couple of times in a row with the same auth method (Firebase rules are open, so everybody can edit and see the sample inventory).