Variable Transparency for Pie Chart Symbology

[PaulLee]

Make is so that pie charts can be variably transparent.  It does not seem that that is possible currently.

In my case, the pie charts are sitting over (and obscuring) mapped locations.  The pie charts seem to move about for some things (e.g., maybe labels), but they don't move for mapped locations.  Actually, moving off wouldn't be/isn't as good as variable transparency.

[KoryKramer]

I realize this is an old idea, but now with pie chart symbology available in ArcGIS Pro, you'd be able to control transparency of any color...