How do I deliver a nested JSON array for content reference with export view display?
I've created a very simple module REST Export Nested to support nested JSON using Views Field Views.

After installing "REST Export Nested":


Install and enable <a
href="https://www.drupal.org/project/views_field_view" rel="nofollow noreferrer">Views Field
Views
Create view display of referenced content (Articles in your case) of type "REST export" or "REST export nested"
Add a relationship to the parent entity and contextual filter of parent entity ID
Create a view display of the parent entity of type "REST export
nested"
Add required fields (e.g. "nid", "title")
Add a field of type "Views field" (e.g. "articles"), configure with
the correct View and display and pass "nid" as the contextual filter


The module doesn't depend on Views Field View and may work with other fields which produce a JSON string.