So it turns out that it was the approach, after all, and the iterator module. I don't think the Adobe rep can actually say that but the solution presented does not even use an iterator but instead focuses on creating a repeater using the HTTP DATA module output only - not that far from what you suggested but with a slightly different approach.
- get the data
- use the number of rows value from data to set a repeater
- compose a string to use in another string - depth
- compose a string within a get ( ) data function, like what you had suggested to get the value

repeater config

first compose string

final compose string (ignore the double quotes and "+" symbols)

actual configuration looks like this:

results
