You can look into the SQLine tool. We recently used to migrate MSSQL to PostgreSQL. For procedures/functions etc you need to have good amount of understanding of TSQL and PL-PGSQL. SQLine will convert 60-80% of you TSQL code. Some manual effort is required at the end.
We want to start migration to POSTGRESQL13 from MSSQL SERVER but we couldnt find any solution for oledb drivers. Please help us to find a solution or any workaround if possible.