DialogService how to use OnOpen

I'm probably blind again - but how do I use OnOpen on a DialogService?

I use a dialog to collect some data, then you "confirm" the data .. Some checks are executed, during those checks you can navigateTo different pages to complete tasks, then my plan is to Navitate back to the underlaying page - check if the dialog was open and display it again (this works already) but now I also want to "re-enter" the "confirm" process. I hope there is something similar to

HandleLocationChanged(object? sender, LocationChangedEventArgs e)

so I found the OnOpen action but this looks counterintuitive as the parameters look very similar to the DialogService.Open call