This post dhows you 2 options to generate a pie chart using single none numeric column. This post expect you know how to get the data from Power BI.
As can see from the below table, there is a column InStatus only consist of Failed and Succeeded.
Click the Pie chart in VISUALIZATION area. Drag the InStatus to Details. Then Drag the InStatus to Values. As you can see it will convert to Count of InStatus automatically.
Another method to do this. Right click the InStatus then choose New measure.
Type the following on the formular bar.
Measure = COUNTAX(MessageLog,[InStatus])
Then you have a new Measure field.
To get the Pie chart. Click on both InStatus and Measure.
You will see the same Pie Chart.