I think the biggest barrier to using these types of apps, IoTs, etc. is the concern about false positives. If you drop your helmet, your bike tips over at the coffee shop, etc. do you have to scramble to get to your phone before it calls 911 or panics your SO?
For a "did you arrive" app the challenge will be not having it trip if you stopped to fix a flat, took a long coffee break, etc.; and conversely if you set it to arrive somewhere 2hrs from now you could be in an accident halfway into your ride and it wouldn't trip for another hour.
I think the detection systems need to get a lot more sophisticated. For example, for a helmet sensor; is the nature of the acceleration consistent with a crash? Can it detect if the helmet was on your head? etc. For a phone app it probably needs to know if the phone is mounted on your bars, in your jersey pocket, or in a saddle bag; since these determine what the phone will experience, and how quickly you can see it/get to it.
ECMGN Therapy Silicon Valley: Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)