Parts of apps can be updated over the air like this, yes
Discussion
Yep; just did it on my Minibits install
The App Store guidelines have changed quite a bit since I last looked at them closely. Ultimately it doesn’t matter what the guidelines say but how Apple enforces them. Glad to hear it’s not a problem. Maybe it’s okay since it’s probably JavaScript executing from WebKit.
Here is a snippet of the guidelines I thought would be a problem.
We'll see but OTA updates are quite common in react native apps. May be they enforce for changing native code only.