Você quer:
CREATE OR REPLACE FUNCTION pick_values RETURN t1_prueba_table
PIPELINED
IS
TYPE t2_type IS
TABLE OF t2%rowtype;
t2_data t2_type;
v_pc t1.pc%TYPE;
BEGIN
-- https://stackoverflow.com/a/67516191/1509264
-- License: CC BY-SA 4.0
FOR cur IN (
SELECT *
FROM t1
ORDER BY pc, r
) LOOP
IF v_pc IS NULL OR v_pc <> cur.pc THEN
v_pc := cur.pc;
SELECT *
BULK COLLECT INTO t2_data
FROM t2
WHERE pc = cur.pc;
END IF;
DECLARE
a_freqs int_list := int_list();
cum_freq INT := 0;
taken string_list := split_string(cur.an, ', ');
idx INT;
c t2.a%TYPE;
BEGIN
a_freqs.extend(t2_data.count);
FOR i IN 1..t2_data.count LOOP
IF t2_data(i).a = cur.ao
AND t2_data(i).c > 0
THEN
-- If there is an "ao" value and it has capacity then assign it to "c"
c := t2_data(i).a;
-- Decrement the appropriate "t2_data" row to show it has been used.
t2_data(i).c := t2_data(i).c - 1;
-- Set the "cum_freq" to 0 so the loop where values are randomly assigned is skipped.
cum_freq := 0;
-- Exit the loop
EXIT;
ELSIF (
t2_data(i).a = cur.ay
AND t2_data(i).c > 0
) OR (
cur.ay IS NULL
AND t2_data(i).a NOT MEMBER OF taken
AND t2_data(i).c > 0
)
THEN
a_freqs(i) := cum_freq + t2_data(i).c;
cum_freq := cum_freq + t2_data(i).c;
ELSE
a_freqs(i) := cum_freq;
END IF;
END LOOP;
IF cum_freq > 0 THEN
idx := floor(dbms_random.value(0, cum_freq));
FOR i IN 1..t2_data.count LOOP
IF idx < a_freqs(i) THEN
c := t2_data(i).a;
t2_data(i).c := t2_data(i).c - 1;
EXIT;
END IF;
END LOOP;
END IF;
PIPE ROW (
t1_prueba_data(cur.pc, cur.vk, cur.ay, cur.ao, cur.an, cur.r, c)
);
END;
END LOOP;
END;
/
db<>fiddle aqui