As you may have heard, the Oracle Database 23ai is available on OCI and as a Free Developer Edition.
Some good blog posts about the announcement:
https://blogs.oracle.com/database/post/oracle-23ai-now-generally-available
https://blogs.oracle.com/database/post/oracle-database-23ai-where-to-find-more-information
https://blogs.oracle.com/datawarehousing/post/23ai-autonomous-database-free
https://blogs.oracle.com/database/post/oracle-database-23ai-now-available-in-the-cloud
Some good videos about it:
Documentation:
https://docs.oracle.com/en/database/oracle/oracle-database/23/nfcoa/index.html
https://docs.oracle.com/en/database/oracle/oracle-database/23/upgrd/index.html