Fly.io is a provider that allows you to deploy backend applications that are converted into docker containers. It also allows you to start up a small PostgreSQL database on their system. By making sure that the frontend is served through the backend you can easily deploy your entire stack on fly.io.

The main drawback of fly.io is that its free trial only allows you to deploy exactly two systems. For a full stack application this would be the backend (which is also serving the frontend), and the database, meaning you would only be able to deploy a single project freely.