The trick is to concatenate the data series values into your pie slice label, as follows:
Example 1 for count
| stats count by op_eTOM
| eval op_eTOM_Slice=op_eTOM+ ": " + count + " Transactions"
| fields op_eTOM_Slice, count
Example 2 for total durations
| stats sum(Duration) as sum_Duration_Seconds by op_eTOM
| eval total_Minutes=round(sum_Duration_Seconds/60)
| eval op_eTOM_Slice=op_eTOM+ ": " + total_Minutes + " Minutes"
| fields op_eTOM_Slice, sum_Duration_Seconds
Yes.
(perhaps you'd be so kind as to provide more details, so I/we can give you an even more useful answer?)