If you use a weight scale from Medisana, you can only sync your weight stats with the Vitadock app and website. As I could not find any way to get these data into Garmin Connect, I wrote a converter which you can find at https://reuneker.nl/files/vita/. It's limited in the sense that it only allows you to import your weight (so not BMI, bone mass et cetera), but it works.
Photo by i yunmai on Unsplash