Pulumi: Instead of using Output.Tuple, how can I reference a single parameter to access a future value?

Question

Instead of using Output.Tuple to access a future value of a resource (yet to be created), how can I use only a single parameter to accomplish the same thing?

Note: I tried using Output.Create and observed a resource not found exception.

Code:

var appResult =
    Output.Tuple(functionApps.First().Name, functionApps.First().Name) // I shouldn't need a tuple for this
          .Apply(async tuple => await

              ListWebAppHostKeys.InvokeAsync(new ListWebAppHostKeysArgs
              {
                  Name = tuple.Item1,
                  ResourceGroupName = resourceGroup.GetResourceName()
              }));

var functionKeys = appResult.Apply(r => r.FunctionKeys);