How does one deploy a backend application e.g. NodeJS in IPFS

I have found examples of deploying a frontend web app in IPFS but haven’t found one on a backend app. How is a project like Orbit able to run on IPFS? Is it deployed on IPFS?

Or does someone have to deploy an application to AWS, GCP, Azure etc and then call the IPFS APIs from there.

Thanks for your answers.