You can create entirely custom tooltips for pie charts with the mendix Charts – Pie Chart widget.

As you can see in this example here.

https://charts102-sandbox.mxapps.io/p/PieChartTooltip

Is this what you are looking for?

I'm not sure about pie chart, but in at least in bar charts you can influence almost any aspect of the chart using plotly.

Put the chart into developer mode and enter the plotly code here.

https://plot.ly/javascript/reference/ is a good source of reference.

I had been reading that but didn’t find a way to specify a sum(field) to add to my hover label? I see mainly formatting options.

Yes, thank you – but I haven’t been able to figure out how to configure the tooltip to show the data value?