This is a demo tutorial. While there is no step-by-step commentary available (yet), the live demo below is fully functional. Feel free to open it for full source code.
These two demos show how we can use adapters to selectively display labels outside some of the Sunburst slices.
Labels on last level
This demo puts labels outside of slices for the outside series.
Labels on child-less slices
This demo shows how we can selectively display labels outside of those slices that do not have any children of their own.
See the Pen amCharts 4: Sunburst Diagram (outside labels, adaptive) by amCharts team (@amcharts) on CodePen.24419