So your requirement with cellular calling (eSIM) is already fairly restrictive and depends on which market we're talking about. Where I live (.se) you get to choose between Apple and Samsung and since Apple was out of the question, you're stuck with Samsung.
Not entirely sure if your second requirement with long battery life can be fulfilled. You'll be charging the watch every day, probably more often if you take calls on it.
There's some rumors that Garmin Forerunner/epix will get eSIM support, but that will be also carrier dependent.
These wearables are pretty complicated high end devices, I wouldn't really give them to elderly parents who stuggle using a normal mobile.
I think it might be better to look into other tyoe of devices like pager systems from caregivers, if you're worried about health issues.