I just bought a VS4 to use when not wearing my Fenix 6X Pro Solar.
It is great that steps/HR/calories get synchronised between the two devices but what about Body Battery and Stress?
those are firstbeat products, not garmin, so i guess they do not have the rights / patents/ code, etc. but now gamin bought firstbeat, so it might be a chance... i asked them here:
..may be others will do it to...
My stress synchronises; but not body batter or pulse ox