How to set up a 'review-like' view that connects users to nodes?
I've created these types:


Item (node) : has entity reference field to node of type endorsement.
Endorsement (node) :  has entity reference field to user (which I guess has role advocate in your case)


The View:
Base table of nodes, filtered by type 'Endorsement'

Two relationships:


A bridge to the Content entity that is referencing Content via field_endorsement (as we have nodes of type endorsements in our base table, we need to link it to 'Item'. 'Item' has the entity reference field containing endorsement, hence we go in reverse: ie referencing)
A bridge to the User entity that is referenced via field_advocate (as we have nodes of type endorsements in our base table we need to link it to User. Endorsements has an entity reference to user, hence it is a simple forward relationship, ie referenced)


Now add the Contextual filter of type nid. Set its relationship to 'Content referencing Content from field_endorsement', which was the first relationship added. The nid we are passing it is of type 'item', hence we must link it via the relationship to 'items'. Set 'hide view' 'when filter value is not available'.



For argument input: From panel argument, First argument.

Add your fields as you want. There is no need to add nid as a field unless you need to do so for a specific reason.

done with the view, back to the panel: add the view to the panel content for the page, and tick 'Send arguments'