I am trying to add Authentication in my flutter app without using the universal login. I am using my custom UI of my flutter app and NodeJS as a backend. so far I achieved login with email and password, reset password, verify email etc. using the NodeJS API that uses auth0 NodeJS package and now I want to add social Signin like Google, Facebook etc to my flutter app and connect them with auth0 though by NodeJS backend if required.
Go to native app setting in auth0 and enable social login
Use Facebook sdk on flutter for login, and get access token on successful login
oauth/token - use this endpoint to exchange facebook token with auth0 token
Refer