[bhelkey]

If they open source it but the app isn't allowed on the app store, how will anyone install it?

[post-it]

If they're on Mac, they can import it into XCode and install it as a development app.

[freehorse]

In my understanding it can be allowed as long as they do not market it as medical app?

[slowmotiony]

We've been sideloading iOS apps for years without any issues. You can use Xcode, or sideloadly, or altstore, or like a hundred other ways.