That's a bit of an extrapolation though, isn't it? Many people simply run VMs that connects to some arbitrary pgsql instance, which might happen to be on RDS if

That's a bit of an extrapolation though, isn't it? Many people simply run VMs that connects to some arbitrary pgsql instance, which might happen to be on RDS if they want to simplify the management of that. Those VMs can absolutely run almost anywhere, and they can connect to just about any instance of pgsql. I heavily use many services on AWS, but can quite literally move the entirety of it to my own servers, Google, Azure, or elsewhere in very short notice. People can choose to use some of the more unique services, but that is not related to RDS.