Interesting question. Mainly as mentioned above we needed Google Play Services for AR. Nothing else stands out at a high level.

However there is a clear bottleneck with the Google AR team for features that the community really wants. While it's understandable, perhaps the open source libraries aren't the priority or there's short staffing, there are issues like this one - https://github.com/google-ar/arcore-android-sdk/issues/153 - that have been open since Jan 2018. This one asks that we can use the smartphone flashlight simultaneously with ARCore, but there's no visibility on how close we are at the moment. This feature would have likely improved our work's performance greatly, but even in general, many other AR developers are asking for it.

Re: overcoming it, there's not much we can do in this case. We just didn't implement the feature.