You really know what’s important in life, keep trying to hold onto that.
I’d say try the AW, it’s difficult for someone else to give you the answer. I use just my watch when out for walks four times a day. Sometimes I listen to podcasts or music (AirPods), so I’m just pointing out you could be less unplugged than you want. I opt not to get message notifications on my watch unless they’re emergency. Practicing self discipline is likely more what you want, and possibly just setting up Focus modes on your phone might help. I have mine set up to change focus modes and make my phone what I need it to be at certain hours of the day. Hope that helps some!
While you can set up as family without him having an iPhone, he will need his own phone for use of the health app as you described. Also if he’s a fall risk, consider the cellular model because it can call emergency without a cellular plan.
It is easy to find a cheap iPhone. He wouldn’t even need cell service to use it with the Watch, it could be used as an at home Wi-Fi device only. Refurbished would be fine if you are smart about checking to make sure it isn’t locked to someone’s account. Places like tracfone often have new but older models and if you hit it right there are sales stacked with coupons.