SQL Pivot with GA4 Data in BigQuery

Question

This is my original query using GA4 data in bigquery to understand the depth of engagement, looking at 01/22

SELECT active.num_days_active, 
COUNT(DISTINCT active.user_id) AS num_users 
FROM (
  SELECT a.user_id, COUNT(DISTINCT a.event_date) AS num_days_active
  FROM `test.events_202201*` a
  WHERE _TABLE_SUFFIX >= '01' AND _TABLE_SUFFIX < '31'
  AND stream_id = '1' OR stream_id = '2'
  GROUP BY a.user_id) AS active
LEFT JOIN `test.events_202201*` a2 ON a2.user_id = active.user_id
WHERE a2._TABLE_SUFFIX >= '01' AND a2._TABLE_SUFFIX < '31'
GROUP BY active.num_days_active
ORDER BY active.num_days_active ASC;

It returns this, only showing a few rows but essentially counts the number of distinct days a user_id has had an event

num_days_active	num_users
1	36491
2	16428
3	9577
...	...
31	22

How would I pivot this, to show this for each month of this year - I can't seem to get my head round it. Would it need to be a dynamic pivot?

In the table schema event_date is a string.

I want to return the below table, for each month of the year

num_days_active	January	February	...
1	36491	35211
2	16428	13445
3	9577	5000
...	...	...
31	22	50