The problem isn't developing on device, it's importing code/dependencies. Apple doesn't want apps that can download and run arbitrary binaries from the internet. My understanding is that they have interpreted this broadly in the past as basically "any code that the end-user didn't type by themselves or hasn't been vetted by the app's author".

Again, my understanding is that this has historically thrown a huge monkeywrench into builds and dependency-resolution, for example you cannot include something like Maven. However, apparently this is OK (presumably as long as you stick to the official DotNet library set).

Stuff like git is really in a grey area. Apple won't officially approve it themselves, but they have approved some scripting tools for which people have implemented git.

Well, having just got a runtime error, I can tell you why it doesn't violate anything - it is running as an interpreter on device.