You can use a bind variable declared in SQL Developer to hold and show the results:
var r refcursor;
exec myPackage.mySPTest(P_NOTIFICATION_ID => 1975357, P_CURSOR => :r);
print r;
exec
is shorthand for an anonymous block so this is equivalent to:
var r refcursor;
begin
myPackage.mySPTest(P_NOTIFICATION_ID => 1975357, P_CURSOR => :r);
end;
/
print r;
Unless P_CURSOR
is declared as something unhelpful, maybe...