Migrate SQL Server binary datadump to postgresql
What you are seeing is SQL Server data pages in a backup file. Or a SQL Server data file (.MDF). Either way, is is a collection of 8k data pages.

These would be restored or attached to a SQL Server. 
They are not conveniently readable without a SQL Server install.

No SQL Server = no access to the data. Quite simple.

If you don't have access to a SQL Server install, why on earth do you have a SQL Server data file/backup? What do you or your source expect you to do with it?

So, your solution is clear: ask your source to export the data to CSV and provide the database design.Then you implement and import into PostgreSQL.