Sorry, forgot to mention, and this is less about using it for exercise so I'm making a new post instead of editing an already long one that's hopefully more on topic.
If you use Android, a watch makes a great "smart lock."
(Meaning you leave your phone locked, but don't have to unlock it because the BT connection with the watch acts as a key.)
If you use your phone for music at home, the music controls in the watch mean you can skip or replay a song while you're cooking, change the volume, etc.
If you carpool - which kind of went out of style given the pandemic - you'll see the "I'm on my way" text while you shower.
It's not a full on smart watch, any of the Garmins. But it's enough smarts to let you set your phone down and forget it.