If you have selected Postgres and Oracle as the supported databases, Jmix Studio should have generated Liquibase changelog files suitable for both these databases. For example, if your entities have UUID primary keys, the table definitions should use the ${uuid.type} variable for PK columns, and this variable is defined as uuid for Postgres and as varchar2(32) for Oracle.
So the same set of Liquibase changelogs should be executed successfully on the Oracle database if you switch the Data Store in the project to Oracle.