You can't do all that data massaging in a single step with COPY, but you have many options for that ETL process. Some examples: * http://pgloader.io/ is a good tool for data manipulation and fast loading. Whether that works with JSONB or not, I cannot say, but it should be straightforward to find out.
* COPY your data into a staging table, and load your production table with an INSERT ... AS SELECT ... command, where the SELECT is doing conversion to JSONB.