What needs to be done

Drupal

1. Expose Layout Builder data to REST and JSON:API. https://www.drupal.org/project/drupal/issues/2942975
2. Decoupled admin theme. (Would be nice to have)
3. Decoupled Router module should support resolving routes for all entities like views.

Angular

The demo can be seen here: http://deverything.xyz/. The content for this is coming from https://abh.ai.

1. Basic Page using layout builder.
2. User page.
3. Taxonomy terms
4. Home page and other basic site settings like site slogan, etc.

React

1. Everything.