Combining google auth 2 with personal refresh and access tokens in express

Question

I'm new to authentication and I created a personal authentication that works by creating a refresh token, storing the token in my MONGODB database and using it to generate access tokens that constantly authenticate the user. I'm using Angular as the frontend framework, and I use the HTTP Interceptor to get the tokens from the headers and store them in my local storage, then append them to every single request I make. This all works fine, but I'm trying to implement Google SignIn, making use of passportJS and I can think of no way to make it work with my personal authentication. Any suggestion is welcome. Thank you