How to do automatic login to a website with an Ionic app?

I have a Drupal website that has a ton of content.

I have built an Ionic app for Android to access some of the content via the Drupal site’s JSON:API. The Ionic app user can log in to Drupal with OAuth2 and perform variations.

However, my Ionic app does not implement all the content that is available in Drupal. So at some points in the app, I have added links to my Drupal site. The problem is that when a user clicks a link in the app to go to the website, the user is not logged in on the website even though the user is logged in on the app.

What kind of approach can I use to automatically log in the user to the Drupal website from the Ionic app? Has anyone done something similar? I would really appreciate any hints you could provide.