REST API filtering via array

I have been trying a few different ways to get this to work, and I am at the end of my ideas…

So I have a data set in Google’s Realtime Database. The data represents a bunch of shipments, which each hold some admin data about the shipment, and a list of stops and the data for each stop. Something akin to:

shipments :

shipments : 
<app_user_id> : 
         0 : 
              shipment_id : 12345
              pickup_location : 123 main st
              dropoff_location : 456 Main st
              stops : 
                   0 : 
                        name : bob's shake shack
                        state : MS

the 0’s would increment up as more shipments/stops are added. The numbers being the “keys” to the data come from AppGyver’s requirement that collection data be presented in an array. This is fine and works fairly well for a collection of data records, however I cannot get a single record retrieval to work correctly. My GET RECORD looks like:

<realtime_database_path>/shipments/<app_user_id>.json?orderBy=“shipment_id”$equalTo="{shipment_id}"

I can verify I pass the shipment ID correctly, and that I get the “correct” data, however it comes across like:

{ 0 : {shipment_data}}

Where 0 would be whatever index in the list the shipment is in. Rather than just simply:
{shipment_data}

How do you configure the AppGyver REST API to work with both a collection of records and query for a specific record?

A work around if possible could be do add a “wildcard” response key path. This would then just bypass the index key and give me the data I need. This is super hacky, but would “work”. is there any way to pass a wildcard response key path? Something else entirely?

Appreciate any help on this one.