Yes, after winter20 release we can query metadata decencies using tooling API. So while running this query, "Use Tooling API" checkbox must be checked in developer console.
SELECT MetadataComponentName, MetadataComponentType
WHERE RefMetadataComponentType = 'ApexClass'
AND MetadataComponentId = '00NXXXXXXXXXXXXXXX'
NPSP's Customizable Rollups feature is designed to facilitate complex, filtered rollups of giving data, from Opportunities and Payments, based upon hard or soft credit mechanics.
The feature doesn't provide fully generalized rollups of any object to any object.
You can read about the types of CRLPs that are available in NPSP documentation. You've selected ...
Salesforce, for one reason or another, doesn't allow us to make relationship fields that target OLI (OpportunityLineItem).
We can hold an OLI Id in a text field, but that won't allow you to traverse the relationship in SOQL.
Your options here are to break this into two queries (one to pull your Custom_Object__c records based on the Ids of the OLIs you are ...