Oracle – How to Migrate a Big Database from Oracle 11g to 19c

It sounds like Oracle Total Recall may fit your needs:

Regulatory oversight such as Sarbanes-Oxley, HIPAA, and Basel-II, as well as internal audits, require companies to keep historical data available for long periods of time. Oracle Total Recall, part of Oracle's comprehensive portfolio of database security solutions, works with Oracle Database 11g, Enterprise Edition to help companies store their data in secure, tamper-proof databases while keeping it accessible to existing applications

The documentation states that it can support refactoring:

In Oracle Database 11g Release 1, the Add Column DDL operation is supported with Flashback Data Archive. With Oracle Database 11g Release 2, the following DDL operations are supported, with full support for Flashback queries across all associated changes:

• Add, Drop, Rename, Modify Column

• Drop, Truncate Partition

• Rename, Truncate, Drop Table

For more complex DDL – upgrades, split table, etc. – the Disassociate and Associate PL/SQL procedures can be used to temporarily disable Flashback Data Archive on specified tables.

I don't think any other ports than the listener ports are required. I suspect that the ports need to be open on your source AND target database/firewall, allowing both incoming and outgoing connections. Also, the host running RMAN has to be able to reach the listener ports, but that's probably default.

If tnsping works to both servers from the host you are running RMAN from, i think you should be all set.