How to generate rows for gaps in data with various gap scenarios

I've been unable to find an applicable available solution. Our inventory table does not have records if a product has zero inventory in a specific location. The table updates daily with a new record for the previous day.
I'm trying to create a query that outputs the data in my inventory table but also creates a record for the missing dates with an inventory quantity of zero grouped by product_id and inventory_location_id vs. no record at all.

Here's some example data from the inventory table:

Scenario 1 - Gaps in dates in specific inventory_location_id.

raw table data:

Scenario 1 - DESIRED QUERY OUTPUT

Scenario 2 - Open gap in dates in specific inventory_location_id.

raw table data

Scenario 2 - DESIRED QUERY OUTPUT

I've tried the following queries:

SELECT
  dates.day,
  t1.product_id,
  t1.inventory_location_id,
  COALESCE(t1.inventory,0) AS qty
FROM (
  SELECT
    *
  FROM
    UNNEST(GENERATE_DATE_ARRAY('2020-01-01', CURRENT_DATE(),INTERVAL 1 DAY)) AS day ) dates
LEFT JOIN
  inventory_table t1
ON
  dates.day = t1.date

and

with dates as (
  select day
  from unnest(generate_date_array('2020-01-01', current_date(),INTERVAL 1 DAY)) as day
),
temp as (
  select *, lead(date) over (partition by product_id, inventory_location_id order by date) as next_day
  from inventory_table
  order by product_id, inventory_location_id, date
)

Select day, product_id, inventory_location_id
from dates
join temp on dates.day = temp.next_day

neither have resulted in getting null values from the inventory table, let alone being able to create a record showing 0 as the inventory quantity for the missing dates.

I also attempted a similar query using a cross join, but that query timed-out.

Really would appreciate help on this one! Thank you in advance!

Use below approach (BigQuery Standard SQL)

WITH dates AS (
  SELECT DATE, product_id, inventory_location_id
  FROM (
    SELECT product_id, inventory_location_id, GENERATE_DATE_ARRAY(MIN(DATE), CURRENT_DATE()) dates
    FROM your_table
    GROUP BY product_id, inventory_location_id
  ), UNNEST(dates) DATE
)
SELECT * REPLACE(IFNULL(inventory, 0) AS inventory)
FROM dates
LEFT JOIN your_table
USING(DATE, product_id, inventory_location_id)
ORDER BY DATE DESC    

if applied to sample data in your question

WITH your_table AS (
  SELECT DATE '2023-07-12' DATE, '05427' product_id, 31 inventory_location_id, 115 inventory UNION ALL
  SELECT '2023-07-11', '05427', 31, 120 UNION ALL
  SELECT '2023-07-10', '05427', 31, 120 UNION ALL
  SELECT '2023-06-27', '05427', 31, 5 UNION ALL
  SELECT '2023-06-26', '05427', 31, 6 
)       

output is