Your definition of emergency communication is way off. Sure you can use some app for training for that situation, however it’s the least reliable way to get communications out in an actual emergency where others are actually going to hear and respond to it.
The best communications in an emergency, are those that are the most widely used. Which would be voice first, CW second. Having to carry around a phone, to use some app that someone else has to be actively listening to using another phone that is held up to a handheld, is not how I would want to be doing things in an actual emergency.
I also wouldn’t rely on vara during an actual emergency. Sure a it’s fun to play like using vara or a ht held up to a phone is going to help in any way during an emergency, but if you are relying on them, you are doing it wrong. I certainly wouldn’t want my life to depend on them.