If anyone would be interested, I managed to build this non-circular chart. You can see the effect in workbook attached.
I think this chart is good to show structure or flow, reducing the number of marks displayed (e.g. comparing to Radial Treemap).
In this example, number of marks to display was reduced from 5684 marks (Radial Tree) to 28 marks (Gantt Tree). Quite useful if your reports need to perform fast!
Gantt Tree.twbx 25.0 KB