All-auth with REST framework

I’m trying to connect my website to the mobile app with API but I am having trouble with authenticating the users via Gmail account from mobile app. I think there is not good resources for this topic even though some resources explain how to authenticate with bilt-in login system. For me, I am using a library named retrofit2 because I’m working on mobile app but any framework is okay (like React, Vue etc.). I want to know how to implement and how I can test if it can be authenticated.