Smart watch for follower

My son is using xdrip+ with nightscout update and I have night guard on my iphone and I carry an android phone with xdrip as follower just so I can get real time alerts.
I thought about purchasing a smart watch such as Samsung watch 3 in order to install xdrip and get rid of my android phone, but I was not able to find anywhere that this is possible.

Does anyone have a smart watch with xdrip as follower but with iphone? Which phone? What is the installation process?
Any other idea for getting real time alerts with iphone will also be much appreciated.