That's really helpful! I just checked on this and you need to enable 2FA as well:

"Health data can be stored in iCloud. End-to-end encryption for Health data requires iOS 12 or later and two-factor authentication. Otherwise, the user’s data is still encrypted in storage and transmission but isn’t encrypted end-to-end. After the user turns on two-factor authentication and updates to iOS 12 or later, the user’s health data is migrated to end-to-end encryption."

https://support.apple.com/en-gb/guide/security/sec88be9900f/...