Need to have Apple Watch 4 auto-answer calls

I have an elderly family member with dementia, for whom I’ve purchased an Apple Watch 4. His iPhone is set up to auto-answer calls via speakerphone after 8 seconds, but ONLY calls on his Favorites list are allowed through. He refuses to carry the cell phone with him, though.

I’d like to have the Apple Watch do the same thing, but there doesn’t appear to be any auto-answer or raise to talk (without using Siri). He will NOT remember to press the green phone icon to answer (although it is easier to get him to do that than to swipe to answer an iPhone). I’ve looked through all the Accessibility features but don’t see. Way to accomplish this.

This would be amazingly helpful to those of us who need to keep track of elderly loved ones who don’t like the idea of carrying a cell phone, and refuse wearing all of those ridiculous-looking GPS devices for wanderers, but are still willing to wear a watch.