Kardia isn’t really compatible with iPhone health or watch. Neither shares data and they won’t bc kardiacare. So what is besides the apple watch?

There have been legal issues between Kardia and Apple that may be interfering with any progress, but there seems to be an app for the iPhone. You will need to ask Kardia how to interface with your iCloud Health data if you already own the Kardia, or check this out Sync a third-party workout app to Fitness on iPhone – Apple Support (UK)

Series 3 watch should never have been sold for as long as it was. Getting it to even pair with an iphone 12 is a skill in itself. You can get a series 7 Watch quite reasonably these days, I saw one for just over £300 in the UK in a catalogue store clearance.

I have the same problem Beurer. I have Beurer BM 96, which can record ECG/EKG.

Its app can share all of the data except EKG (or ECG).

Beurer's app can share blood pressure, pulse, etc.., but ECG's sharing is not available.

The problem may be

• Apple or
• lack of standardisation or
• legal issues

With ECG it is usually legal