Hello,
I have a pie chart that displays all values. I would like to have a dashboard viewer be able to select a single pie slice and the value of that selection would populate a parameter. If not selected, the parameter would keep the default value of all.
To set a parameter with the value, choose Navigation Action. You can target the same sheet or a different sheet and set a parameter with the value of the pie wedge clicked.
@PhilK, As @aswilson suggested you will have to use navigation action to set parameter with the value you select from the visual. Please refer to below link for additional details.