It does seem great, but the battery life seems a bit on the lower range. Three to seven days might be more appropriate for an amnesiac who also might be a bit confused with the nature of charging it.
Self winding watches were a thing for quite some time.
Definitely still a thing. I'm wearing one right now. :)
I wonder if something like this could be adapted to work for this use case? The big problem I see is that a human can just take the damn thing off, and people with dementia are not incredibly reliable or predictable.