I don't know if it's an option or not but this reminds me of a very early computer game that I played in the evenings after having a nice Brontosaurus steak for dinner. 😀 I got "stuck" in the game and it wouldn't let me move up, down, left, right, forward, or back but kept asking me what I wanted to do. I was ticked off because it seemed like it was an easy black'or'white question. That's when it struck me and I typed "change color" and it let me proceed.

The problem is similar here. You have SQL Server on two boxes on one side and they have absolutely no problem with data transfers from one to the other. You want to get the data to another box with a different SQL engine and are having great difficulty in doing so. You'll continue to have this problem for future "adventures", as well.

Since SQL Server has some nifty and high performance built-in tools to transfer the data, wouldn't it be easier, at this point, to "change color" and redact the Postgre SQL Server to be an MS SQL Server (SQL Express might even be enough and it's FREE) to solve not only the current problem but all future problems of the same and different nature?