Which wrist? It doesn't matter.
It also doesn’t matter which way the buttons are oriented.
What does matter is that your Watch is set for whether it is on your left or right wrist, and whether the buttons are oriented left or right.
Wearing a heavy coat or gloves can influence which way the buttons work best without encountering spurious button presses from the sleeve or the gloves, as can whichever way the buttons oriented that’s easiest for you to use.
The watch, its sensors, and such are ambidextrous. Set it as you want it worn, and it all works. For those folks with a dominant hand, wearing it on the non-dominant wrist makes it easier to manipulate the controls, and possibly less likely to get slammed into something. Nothing more.