Oracle 18c

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CREATE TYPE a_obj IS OBJECT (
  a1 INTEGER,
  a2 integer
);
CREATE TABLE a OF a_obj (
  CONSTRAINT a__a1__pk PRIMARY KEY (a1)
);
INSERT INTO a (a1, a2)
SELECT 1, 2 FROM DUAL UNION ALL
SELECT 3, 4 FROM DUAL;
2 rows affected

-- db<>fiddle does not know how to display the object type...
-- but the query works without errors.
SELECT OBJECT_VALUE AS value FROM a;
SELECT VALUE(a) AS value FROM a;
ORA-00904: "A": invalid identifier

SELECT VALUE(a_alias) AS value FROM a a_alias;
BEGIN
  FOR r IN (SELECT OBJECT_VALUE AS value FROM a)
  LOOP
    DBMS_OUTPUT.PUT_LINE( r.value.a1 || ', ' || r.value.a2 );
  END LOOP;
END;
/
1 rows affected

dbms_output:
1, 2
3, 4

BEGIN
  FOR r IN (SELECT VALUE(a_alias) AS value FROM a a_alias)
  LOOP
    DBMS_OUTPUT.PUT_LINE( r.value.a1 || ', ' || r.value.a2 );
  END LOOP;
END;
/
1 rows affected

dbms_output:
1, 2
3, 4