how to add username in firebase auth

So I am using FireBase Auth for users to signin and sign up, but I also want them to have the option of choosing an username, and if the username is taken they have to take something else. How can I do so? because when there is no option for adding username while signing up in firebase auth component.

I’m not sure but if you use Firebase Auth you have to use the data from Google profile, you can start the update block to change the name or other informations.
Another way is to use Google data for the login and after introduce your choice for nickname , then you have to store data together . The name or mail or Id on Google and the nickname on app so you know that user Id= 1234 has the nickname= Pippo