Data cannot be exported or imported between heterogeneous databases due to different data formats. However, if the data formats are compatible, table data can also be imported theoretically.
Generally, third-party software is required for data replication to export and import between heterogeneous databases. For example, you can use a third-party tool to export table records from Oracle in .txt format. Then, you can use Load statements to import the exported table records to the DB engines supported by RDS.