It's easy to set Aurora up as "slave" for accepting replication data from an external MariaDB/MySQL server in order to make a smooth low-downtime migration into AWS, but there are... oddly peculiar kludges... when wanting to set Aurora up as "master" and have it feed its binlog outside in order to migrate away in the same smooth fashion.
For their managed Redis ("Elasticache") they have intentionally disabled a few functions that relate to exporting/migrating live data from one Redis instance to another. In particular the "MIGRATE" function, which is used specifically to make a fast and accurate dump of all data when you want to supplant (read: migrate) a Redis instance. Instead you have to hack manual outbound migration together yourself, key by key, database by database.