Earlier quoted context omitted.
Once you're using an Oracle database, you are probably using proprietary Oracle features, SQL syntax, client libraries, etc. The first chance you get might be a while. I once worked on a project porting an app from Oracle to another commercial DB. When Oracle is deeply embedded in your applications, it's easier said than done.
I'm surprised there aren't entire businesses based around selling compatibility layers or something.
https://www.enterprisedb.com/docs/epas/latest/fundamentals/e...