This video shows how an API could allow the inclusion of user data:
Looking at it, I thought that if the Gramps API allowed the inclusion and storage of external data as it shows, it could answer, at least in part, the needs of some who want, for example, to link Gramps and Zotero.
Seeing it, I imagined that Gramps might display an additional JSON data tab in editors such as the Source or Citation editors (or others) if the API had received such data associated with the source or citation record to display that data and doing no more with that data.
This would allow us to avoid managing these external data in Gramps while still enabling them via its API.