Hey! Author here.

You don't need to put the username of the logged in user into Redux, but if multiple components across different pages need to access this data, you should make it globally accessible.

You can choose Redux/MobX for this, or you can roll your own solution with context and hooks.

I'm actually learning more about the context/hooks approach myself.

Kent C Dodd wrote a great article on this topic I'd recommend:

https://kentcdodds.com/blog/application-state-management-wit...