I am creating the authentication side of a web app using Firebase's Google Sign in and would like to see if the newUser.displayName is unique in the Firestore database. My current code doesn't work as I must create the user before accessing the displayName. If I create the user first and then check the displayName, that would cause problems as I would need to go back and delete the user if the condition is not met. Is there a way to access displayName before the user is created?

Signup.js

const handleGoogleSubmit = async (e) => {
        e.preventDefault();
        setError('');
        try {
            const available = await usernameAvailability(newUser.user.displayName.replace(/\s/g, ""))
            const newUser = await signInWithGoogle(email, password);
            const { isNewUser } = getAdditionalUserInfo(newUser) 

            if (isNewUser) {
                await setDoc(doc(db, "users", newUser.user.uid), {
                    email: newUser.user.email,
                    uid: newUser.user.uid,
                    username: newUser.user.displayName.replace(/\s/g, ""),
                    usernameLowercase: newUser.user.displayName.toLowerCase(),
                });
            }
            navigate('/account');
        } catch (error) {
            setError(error.message);
            console.log(error.message);
        }
    }

AuthContext.js

const usernameAvailability = async (username) => {
        const q = query(collection(db, "users"), where("usernameLowercase", "==", username.toLowerCase()));
        const querySnapshot = await getDocs(q)
        console.log(querySnapshot.empty, 'querySnapshot.empty')
        if (querySnapshot.empty) {
            return true
        } else {
            throw new Error("Username already exists")
        }
    }