Getting a query as a delimited text list

I have two tables Pieces(Child) and Pallets(Parent) that are related. I am trying do a query that will allow me to get a list of all of the pieces related to a project where a Quality Control Checkbox is true in a character delimited list and then post that list to a text field in all of the Pallet records related to that same project.

As of right now I am trying to do this in a pipeline using a json webhook request and I imagine it is possible with jinja, but I'm unsure of the exact syntax to use for the query to get the output I want. The body of my webhook request is as follows:

{"to": "brctf4aiw", "data": [{"76": {"value": "
     {"query": {
          "tableId": "brcfcrnpx",
          "filter": "{15.EX.{{a.bid_project_number}}}AND{50.EX.'True'}",
          "fields": [6]}
     |trim|list}"
}}
]
}
------------------------------
Ben Krieger
------------------------------