sharepoint online – Can I leverage the built-in Duration Field in a Events List

Trying to add a view to a spo event list that get the total duration of the events in the list. I found a built-in Duration field accessible though PNP Powershell (e.g. $event.fieldValues.Duration) that seems to be reporting duration in seconds. I can add the field to a view using Add/Set-PNPView, but when I try adding -aggregations "<FieldRef Name='Duration' Type='Sum'/>" to the command, I get count=undefined on the list view.

I’m not used to using the -aggregations parameter so I’m not sure of the syntax and have found documentation to be fairly thin on that point.