You may want to assess how you want to store and access the data in Postgres before deciding on an import strategy.
I have a system with a mix of relational and JSON data. The data was originally sourced in flat file format.
I wrote a few Python programs to take the data, then format to JSON, which I then submitted to pg functions.
To make life easier, I submitted it as 1 JSON field to be decomposed by Postgres into relational data, and another to be loaded straight into pg JSON columns.
The functions then either strip out the data from JSON using the PG JSON functions and store it relationally, or plug it straight into a JSON data element.
Not terribly difficult to do, especially if you are not navigating complex JSON structures in pl/pgsql to strip out the data.
Plenty of python JSON examples out there. Less so for PG :)