> the DSL is just opaque to me.

May I suggest "gron"? As compared to jq it is simpler (good!) has less features (good!) has no DSL (good!) and it is less powerful (good!, in many cases). It is a tool that "expands" json into standalone lines, and you can further process them using the standard tools grep, sed, cut, sort, awk...

EDIT: for example, if you have this json:

    {
      "outdir" : "out3",
      "data" : [
        {"img" : "img_01.jpg"},
        {"img" : "img_02.jpg"}
        ],
      "roi" : {
          "x" : 150,
          "y" : 150,
          "w" : 700,
          "h" : 700
      },
      "margin_h": 20,
      "margin_v": 5,
      "tile_size" : 300,
      "resolution": 0.5
    }

running it through gron produces this

    outdir = "out3"
    data[0].img = "img_01.jpg"
    data[1].img = "img_02.jpg"
    roi.x = 150
    roi.y = 150
    roi.w = 700
    roi.h = 700
    margin_h = 20
    margin_v = 5
    tile_size = 300
    resolution = 0.5

that some people find really convenient to deal with.