Exporting of form data supports CSV or XML format. Afraid I don’t know PostgreSQL to know if either of these formats are supported but I would expect that it would allow the import of csv ?
But also, have you looked at how you can set up a report (like you build a form) where you can report online/real time as well? you may find you can achieve a lot there and avoid the need for manual actions in a lot of cases
if you are looking though at the Connection agent to insert/update data directly from a form into your database, I’m afraid it doesn’t support this database at the moment