It’s best to Start/record in the app but not start from the watch. If you start on both you’ll get a double recording.
But I’m sure I’ve used only the watch before. Maybe opened the app and made sure the watch is connected.
The watch has gps though.
There’s also the niggle of using the widget that say “outdoor run” only or using the button menu and selecting the exercise type.
It’s all over the place to actually get working where you’re confident you’ve done it correctly.