My view is that you put something on FB for all the world to see then dont be surprised when they do.
I am surprised they contravene the GDPR when they have a valid relationship with them as a customer.
I have this one, on the android app you can set the heart monitor frequency ~ mine is set to continuous. My only criticism is that the display is a little to dim.
As Leigh said FB like anything else, it is what you make it.
I have no personal data on there and no 'friends' what I do have are connections to lots of special interest groups and news feeds. I find it invaluable.
It reminds me of when I used to get terrible migraines at weekends, it turned out it was a withdrawal from the 10 cups of tea I was drinking a day at work during the week.
It's like comparing footballers from now with those from the 60s, how would Messi and Ronaldo have coped with the muddy ploughed fields that the grounds became after a long hard winter ~ so unlike the billiard flat surfaces of today.