Automatic login across multiple wordpress sites with SSO / silent login

How can I achieve seamless ‘logged in’ experience when my users move across a number of WP instances, comprising parts of our MVP application?

It would need to work for new users and thus create the user in each instance as they move around and also for existing users. Basically anyone logged in to Auth0.

I would really appreciate help (or any hacks) to get this working.

BTW, that “select two tags” thing is a real PITA!

Silent Authentication

Some similar issues:
https://community.auth0.com/t/already-authenticated-wordpress-plugin-single-sign-on/32587

https://community.auth0.com/t/multiple-domains-wordpress-one-login-for-all-and-share-data/25488