extracting SSIS package source code from SSISDB Catalog deployed projects using TSQL

I need to search all the SSIS Projects deployed on a server SSISDB Catalog for a specific substring. My idea is to write a SQL Query on SSISDB.catalog views and internal.package tables to access the package_data field, which is of type varbinary(max) and I was thinking it might contain the package source code, but I found out that this column is always null. Using SSMS it's possible to export the ispac files for deployed projects, therefore the package content it's hidden somewhere. So the question is: how can i extract the ssis pacakges source code using TSQL? this query retuns no rows on my SQL Server 2022 instance SELECT TOP (1000) * FROM [SSISDB].[internal].[packages] where package_data is not null