Apple Watch for teenager with Autism and Epilepsy

My son loves his iPad — must has had 5 or 6 of them by now. He is 15 with Autism and Epilepsy. He goes to school. He's verbal. He can handle basic self care. He has seizures.

We want to get him an Apple Watch with GPS/Cell so we can pinpoint his location and hopefully capture more data around his seizures. He really does not need an iPhone, but I'll get him one if necessary. I see three possible ways to power his Watch: A) Family Set Up, B) Tied to an older iPhone without Cell Service, C) Tied to an older iPhone with service.

Option A does not seem to offer all the features we might want. Sleep Tracking and Blood Oxygen are missing. I base this on the following: Set up Apple Watch for a family member - Apple Support. Just above "Next Steps" near the bottom, it says: "The following features and apps are not available: Medications, respiratory rate, irregular heart rhythm notifications, ECG, Cycle Tracking, Sleep, Wrist Temperature, Blood Oxygen, Audiobooks, Remote, News, Home, and Shortcuts." Respiratory Rate would be helpful and Medication tracking would also be nice.

So would Option B work? Will an older phone with no cell service fully power an Apple Watch? Could I get a sibling a new phone and use their old phone without a SIM and Cell Service to fully power his watch? I'd basically keep the underused iPhone at home and the boy would roam the countryside with his watch. I'd peak into the iPhone from time to time, especially if he has had a seizure to see if any of his health stats show a pattern before a seizure.

Or do I go Option C and pay $50 or so a month for another cell line?

Finally, the URL above also has this nugget at the bottom under Availability of features:

Health and fitness features:

• High and low heart rate notifications are available for users 13 and older.
• Heart Rate Variability (HRV) is available for users 18 and older. 
• Walking Steadiness and Fall Detection are available for users 18 and older.
• Users under the age of 13 can use move minutes, rather than active calories, for their Move goal in the Activity app.

Does this mean that bullets 2 and 3 (emphasis added by me) not work at all for a 15-year-old or are they only restricted in Family Setup (Option A)?

These features would be helpful for finding moments when a seizure is imminent.

I really appreciate your advice on this. I know a lot of families who would like to deploy watches for the same reasons. Hoping to share my experience. Apple's pre-sales support was a bit challenged by these questions. Hoping the user community can help.

Apple User since 1984 • Share holder since Steve came back in 1998 • Owner of an original iPod.