pg_dump for Dum(p)ies

Two months ago, I followed a tutorial to deploy a Phoenix app, say my-app, using flyctl launch; which, asked me if I wanted to create a Postgres database, and I said Yes, and it created my-app-db.

Now, I’m relearning Fly, and I want to issue a pg_dump command and retrieve the backup file. I’ve searched the forum and docs but am confused.

This post mentions doing pg_dump somhow via fly proxy but no details are given; I read the docs on fly proxy but have no idea how to proceed.

Am I supposed to use fly proxy to proxy through an instance of my-app? How to use fly proxy and fly ssh together?