I really like having a compass, I'm not sure why but when I get lost in a town (at night) I usually can find my way back if I know where North is. Some people always know where North is -- not me, but I usually can figure out where everything else is, relative to the North.
I sometimes take walks in the woods with my kids and like to track where we've been. You can do this with a phone but then you have to have the proper app, launch it, etc. I don't like to use my phone for anything else but calls (I'm old). With the Fenix it's just the push of a button.
You can use GPS also to record where your car is, and it will direct you back to it; this is useful everywhere.
Also, as a photographer, if you record your tracks when shooting you can later import GPS data to photographs (some cameras have GPS but not all, it doesn't work too well and it drains the battery).
It remembers my sleeping patterns, which is completely useless but nice to look at, in a narcissistic kind of way.
For me, the point of a smartwatch is that it serves as a secondary interface to my phone. I like that my phone stays in my pocket more, because then I'm less likely to be rude because of my phone, or to have to drag it out just to see what that notification was.
I've owned and used an earlier Garmin watch for running and I loved it, but eventually stopped using it because I just didn't need to maintain another separate device. But clearly you're up to something else than me.