I think I came up with something that seems to work but not sure if this is a good way to do this (I also changed from ScrollView to Flickable because I saw online that it is better suited for touch devices.)

Qt Code: 
  1. Flickable {
  2.  
  3.         id: scroller
  4.         anchors.fill: parent
  5.         contentHeight: main.height
  6.         contentWidth: main.width
  7.         GridLayout {
  8.             id: main
  9.             height: scroller.width > 600 ? scroller.height : children.length * 800
  10.             width: scroller.width
  11.  
  12.             columns: 2
  13.  
  14.             states: [
  15.                 State {
  16.                     when: root.width <= 600
  17.                     PropertyChanges {target: left; Layout.row: 1}
  18.                     PropertyChanges {target: right; Layout.row: 0}
  19.                 },
  20.                 State {
  21.                     when: root.width > 600
  22.                     PropertyChanges {target: left; Layout.column: 0}
  23.                     PropertyChanges {target: right; Layout.column: 1}
  24.                 }
  25.             ]
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Basically I set the GridLayout's height to the height of the scroller or to a very high height (800 * children.length) if the width gets narrower (<= 600 in this case).

Is there a better way to do it or is it "good enough"?