Oracle 21c

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ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS';
CREATE TABLE aux(cat_prod, startdate, enddate, imp) AS
  SELECT 'A1', DATE '2023-01-15', DATE '2023-02-07', 100 FROM DUAL UNION ALL
  SELECT 'A2', DATE '2023-01-13', DATE '2023-01-16', 100 FROM DUAL;
2 rows affected

WITH months (cat_prod, startdate, monthend, enddate, day_rate) AS (
  SELECT cat_prod,
         startdate,
         LEAST(ADD_MONTHS(TRUNC(startdate, 'MM'), 1), enddate + 1),
         enddate + 1,
         imp / (enddate + 1 - startdate)
  FROM   aux
UNION ALL
  SELECT cat_prod,
         monthend,
         LEAST(ADD_MONTHS(monthend, 1), enddate),
         enddate,
         day_rate
  FROM   months
  WHERE  monthend < enddate
)
SEARCH DEPTH FIRST BY cat_prod, startdate SET order_id
SELECT cat_prod,
       TO_CHAR(startdate, 'YYYYMM') AS range_dt,
       ROUND((monthend - startdate) * day_rate, 2) AS imp_range
FROM   months


CAT_PROD
RANGE_DT
IMP_RANGE


A1
202301
70.83

A1
202302
29.17

A2
202301
100