Re: What do you like in ios 15?
This is great - if it worked. On my watch, "No Apple devices found to locate". (Yes, on my phone, Find My iPhone is turned on and my location is set to this device and Apple watches and share my location is turned on.)
iOS 15 and watchOS 8 does this.
On your Watch, open the Find Devices app, select your iPhone, scroll to the bottom and enable Notify When Left Behind.
This is great - if it worked. On my watch, "No Apple devices found to locate". (Yes, on my phone, Find My iPhone is turned on and my location is set to this device and Apple watches and share my location is turned on.)