The Expo setup that I use never calls into Expo servers at build time. For OTA updates, I've managed to get my self-hosted Expo update server working too, although I'm not using it at the moment, as its incompatible with the React Native New Architecture (it's the last expo package to lack this support - hopefully they'll add it soon).
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.
please do so, I would like to build it totally local and when I realize that outsourcing the build to the EAS cloud saves more time and money I will switch later, that sounds like a nice way to get more people use Expo.
I believe it still uses EAS for certificates by default. You can use "prebuild" to get the ios / android directories. Alternatively start a React Native app and install their modules separately. These options still work well but require a lot more setup.
