Can i store data in any other database other than appwrite?

does this mean i can store google or email authentication data in all these instead of appwrite's database?

These are options to act as the backend for the Appwrite Storage service - that is, when you upload a file to Storage, where it actually lives

You can technically have Appwrite use any MySQL (or compatible, eg MariaDB) database as its backend.

But could I just ask, what would be your usecase for using Appwrite Auth, but storing the auth data outside of Appwrite?