Hello,
First, it matters not that the two have an identical structure. There is no passing records between the two.
The answer previously given regarding Calc to Base also applies here for the most part. In your question here you are now dealing with Base as the originator. So now you must extract the data from whatever the source and using that data, then create an SQL statement to update the table for PostgreSQL.
A difference here, especially since this is a remote connection, is the actual code to connect to a remote database. The actual URL will be key in the connection. This code can be seen in my answer in this post → Connect to mssql (ODBC) database via Macro. You can find more details in the document the referred to code was derived from - “Andrew Base” by Andrew Pitonyak found here → Database.
Edit:
Found another of my answers which may help with the URL → Can’t remove password from LO Base connected to MySQL. My answer deals with the connection (to MySQL but others will work) and further info on URL string in comments.