Shiny-proxy openid connect google SSO

Hey, I have an expressJS application and a shiny-proxy application in different domains.

I have set up the shiny proxy application with Google openID as follows:

proxy:
  title: Testx - Open Analytics Shiny Proxy
  logo-url: https://www.openanalytics.eu/shinyproxy/logo.png
  landing-page: /
  heartbeat-rate: 10000
  heartbeat-timeout: 60000
  port: 8080
  admin-groups: scientists
  same-site-cookie: None
  authentication: openid
  openid:
    auth-url: https://accounts.google.com/o/oauth2/v2/auth
    token-url: https://www.googleapis.com/oauth2/v4/token
    jwks-url: https://www.googleapis.com/oauth2/v3/certs
    client-id: <MY_CLIENT_ID>
    client-secret: <MY_CLIENT_SEC>
  # Docker configuration
  docker:
    cert-path: /home/none
    url: http://localhost:2375
    port-range-start: 20000
  specs:
  - id: euler
    display-name: Euler's number
    container-cmd: ["R", "-e", "shiny::runApp('/root/euler')"]
    container-image: openanalytics/shinyproxy-template
  
logging:
  file:
    name: shinyproxy.log

My express server too has a google oidc login with the same client ID and secret. How can I establish SSO between the two?

When the user logs into the express server they should be logged into the shiny proxy application as well and vice versa.