Sync data from Samsung Health to Apple Health on iPhone 13

I've just changed from an Android back to an Apple (13), but I have a Galaxy Watch which is the source of most of my activity tracking. I'm also a member of Vitality health so ideally want all data (step and other) to be pushed to Vitality at the end of the day.

But firstly I noticed that despite installing Samsung Health, and connecting my phone to it such that my activity data is successfully showing up, none of that is appearing in Apple Health.

I have enabled and see the connection in Settings/Health/Data Access & Devices/Samsung Health. In there both "Steps" and "Walking + Running Distance" are enabled. This seems to be working since I see the "phone" steps in Samsung Health. So I think this handles populating Apple-->Samsung.

But the setting on the same screen "Data from Samsung Health" doesn't show any data. So it would seem that data within Samsung Health isn't seen as a source for Apple Health. i.e. Apple<--Samsung

Maybe it's true that Apple can only ever be the source of truth for all connected apps, but that doesn't make sense since the title of this window is "Sources" not "Targets".

So i'm a little confused as to why I see no data in that section.