How to integrate an external open-source identity, such as Auth.js?

Since Squidex/squidex-identity: Identity Server for Squidex Headless CMS has been archived, I searched the documentation and support but didn’t find an answer to this.

I could see the Auth0 provider as a custom social to add Squidex, but it is a commercial product, and I also want to use Auth.js. Do we have anyone who has implemented it?

Sorry, I have missed your topic. Squidex Identity was more like auth0 itself. But if you are self hosting you can integrate auth0 as external identity provider: squidex/backend/src/Squidex/appsettings.json at master · Squidex/squidex · GitHub

When you create a team you can also configure a custom authentication provider:

On te login screen, people can enter their email adress and if it matches to your domain, they will be redirected to your auth provider.