Unable to download ECG apps on iPhone X to be used on Apple Watch series 7

Hi all

My setup:

• iPhone X latest iOS 15.3.1 SN shows originated from Hong Kong
• Apple Watch series 7 latest iOS 8.4.2 SN shows originated from US
• The Apple ID used is located in France (my originated country)
• I am currently living in Cambodia but can have access to other country to login thanks to VPN

All setup has been done really smoothly (amazing Apple compared to Android devices !).

HOWEVER I am unable to download ECG apps "this apps is not available in your country".

After extensive browsing I see that both devices matches the requirements (US HK and France being on the approved list).

I tried to use my iPhone logged in through US, HK and France. All failed.

Can you give me a relevant solution?

Thanks in advance for your support.

Kind regards

MacArthur