How to add missing rows to a table?

Question

Google Sheets

A table is generated using QUERY, where one of the columns indicates the month in YYYY/MM format.
There are sometimes gaps in the returned data, the table is formed with missing months. How to add missing rows by adding missing months and assigning zeros to missing cells?

by converting this:
2020/01 | 443
2020/03 | 112
2020/05 | 244

in:
2020/01 | 443
2020/02 | 0
2020/03 | 112
2020/04 | 0
2020/05 | 244