使用LISTAGGDISTINCT就可以达到这个目的。
LISTAGG聚合函数通过使用新的DISTINCT支持重复消除。
由于您不希望重复的 Package /日期，这是如何做到：

with cte as (
  SELECT p.id, d.date_, pc.pack
  FROM products p
  LEFT JOIN dates d ON p.id = d.id
  LEFT JOIN packs pc ON p.id = pc.id
)
select id,
  listagg (DISTINCT date_,', ' on overflow truncate with count) 
  within group (order by date_) dates,
  listagg (DISTINCT pack,', ' on overflow truncate with count) 
  within group (order by pack) packs
from cte
group by id;

Demo here

您是否尝试过使用STRING_AGG？

SELECT p.id, LISTAGG(d.date, ', ') WITHIN GROUP(
ORDER BY
    d.date
) AS dates, LISTAGG(pc.pack, ', ') WITHIN GROUP(
ORDER BY
    pc.pack
) AS packs
FROM Products p
LEFT JOIN Dates d ON p.id = d.id
LEFT JOIN Packs pc ON p.id = pc.id
GROUP BY p.id;