I would suggest reading some posts from say https://severalnines.com/ who post lots of helpful info. Source: almost 3 years ago

Database configuration - we had to modify the database configuration. This is very difficult in various database providers (like RDS) and may even not be possible. This is also not very uniform between various DB engines (like PostgreSQL and MySQL). - Source: dev.to / 3 months ago

Amazon Database Migration Service might initially seem like a perfect tool for a smooth and straightforward migration to RDS. However, our overall experience using it turned out to be closer to an open beta product rather than a production-ready tool for dealing with a critical asset of any company, which is its data. Nevertheless, with the extra adjustments, we made it work for almost all our needs. - Source: dev.to / 3 months ago

RDS - 750 hours per month of db.t2.micro, db.t3.micro, or db.t4g.micro, 20GB of General Purpose (SSD) storage, 20GB of storage backups. - Source: dev.to / 5 months ago

It's easy to get "database managers" and "managed databases" confused, for obvious reasons. Managed databases are a different product to database managers entirely: they are a service that hosts and maintains your database servers for you, so that you only have to worry about the data inside them. Managed databases are a great way to outsource some of your infrastructure overhead if you don't want to host database... - Source: dev.to / 5 months ago

The app can use a local PostgreSQL and has no issues using a cloud service like Amazon RDS. - Source: dev.to / 7 months ago