Assuming you have not resolved this yet - here is what I have done to parameterise a query parameter
I used custom pagination to let QS provide me with a query template to use the For ... Next loop, initiated a counter (CounterA) to load the pages, and constructed the URL by passing the counter value.
SQL Select .....
With Connection (URL "https://api.example.com/companies?page_number= $ (CounterA)" );
The loop was stopped when CounterA = total count.
Similarly, I am using a preexisting table to read field values and construct the URL to fetch only required details. So I would say yes, it is possible to 'parameterise' a query parameter. Check the documentation at Select REST data with the Data load editor ‒ Qlik Connectors
Also check Bjorn's response here - Re: REST CONNECTOR locate the Authorization token
hope this helps.