I have been a certified/licensed EMT for over 10 years.
"Medical devices are expensive to make."
For many commonly-used devices (ECG, pulse oximeter, etc.), the level of technology implemented is magnitudes less than that of a decent smartphone. Sure, these aren't mass market items--but I'm also hard pressed to understand why it doesn't make sense to have an alternative to a LifePak which easily costs $15K+. Case in point: the AED you can easily buy from Costco in the neighborhood of $1K--and has lots of sophisticated logic. Just because the thing has blinky lights and makes "bing" noises doesn't mean it should be exorbitantly priced.
"People need a manufacturer big enough to sue."
Circular reasoning on the best of days. Does a commercial implementer of this device need a legal team? Yes. Is the pragmatic implementation of a device at lower cost that's reliable and lawsuit-resistant possible? Absolutely.