Dit zou moeten werken voor Windows, Linux en MacOS:

function isEmptyDirectory(aDir:string):boolean;
var
  SearchRecResult: TSearchRec;
begin
  Result := FindFirst(IncludeTrailingPathDelimiter(aDir) + '*', faAnyFile, SearchRecResult)<>0;

  while (SearchRecResult.Name = '.') or (SearchRecResult.Name = '..') do
    Result := FindNext(SearchRecResult) <> 0;;

  FindClose(SearchRecResult);
end;