Is the build job also open source somehow?
I mean that's the case for the 'regular' React Native workflow as well, and most mobile / crossplatform development. That said, yeah getting RN running is a bit more effort compared to Expo, but it allows for a bit more flexibility.
We decided against using Expo because we had a number of 3rd party dependencies (trackers, analytics, chat, sigh) that had native components; it can work with Expo, but the dependency has to implement support for it, and that was a bit all over the place.
The hosted services offered by the Expo team called EAS has an implementation of an updates server that conforms to that protocol. If EAS went away or you wanted not to use EAS, you could write and operate your own server that conforms to the protocol instead.
The Expo framework gives you the module system, runtime environment, CLI tools, debugger, a suite of modules, navigation to build universal native apps. They're universal in that there is an Android build, an iOS build, and a web build, and, especially with Expo Router, they work together with universal links. They're native in that the user experience is native to the underlying platform, usually using system UI components and behaviors.
EAS provides hosted services for building your app, submitting it to the stores, and updating it. Many developers will use both EAS and their own hardware. It is convenient and fast to build locally when iterating on a feature. And it is convenient in a different way to use EAS to make preview builds of your app on your PRs that change your app's native code or to make release candidates for production.
However, as a user reading the Expo docs, I'm not sure if I can separate them easily without deviating from official docs.
Look at the Expo docs on building and deployment, which are essential steps to getting your app distributed. I don't see any mention of how to achieve it without EAS.
There used to be an expo build but it was deprecated a while ago.
https://docs.expo.dev/develop/development-builds/installatio...
"npx expo prebuild" (covered in that link) is a good command to know. It generates "android" and "ios" directories with your Android Studio and Xcode projects, respectively. These projects can be built entirely locally and there is no dependency on EAS.
As a side note, the old "expo build" command also ran on hosted servers. It was part of the old Expo CLI, which, for historical reasons from six or seven years ago, didn't separate the free & open source Expo framework from the hosted offering. We built EAS years later, with a major new feature being support for builds that have custom native code. Keeping EAS decoupled from Expo has been a conscious effort, and we've also designed EAS to work with any React Native app whether it uses Expo or not.
Then again, I can understand why it isn't a priority for the company.
But make no mistakes that Expo is a SaaS with the ability to inspect some part of the codebase.
Everything important for building and distribution process is moving to EAS, cloud-based service that is not open-source and cannot be self-hosted. So if want to build your app using your own VPS, you are out of luck (at least for Expo managed workflow).
Again I'm happy with their service and probably would pay for it when the time comes, but the open-source part is not really the big selling point anymore.