Can "Family" watches really not track Activity or Sleep?

This article details what is and isn't available on a watch set up for a family member without a phone.

If your son is under 13, he can use 'move minues' instead of active calories in the activity app.

Sleep is not available without a phone as it requires more processing power than the watch has.

Set up Apple Watch for a family member - Apple Support

Availability of features and apps

Health and fitness features:

• High and low heart rate notifications are available for users 13 and older.
• Heart Rate Variability (HRV) is available for users 18 and older. 
• Fall Detection is available for users 18 and older.
• Users under the age of 13 can use move minutes, rather than active calories, for their Move goal in the Activity app.
• Users can also measure time in daylight. Parents can view the amount of time their children spend in daylight using the Health Sharing feature in the Health app.

Apple Pay features:

• Apple Cash Family is available to users under the age of 18, allowing them to make purchases and send and receive money in Messages with Apple Pay (United States only).
• Apple Pay using a credit or debit card in the Wallet app is not available with Apple Watch For Your Kids.

The following features and apps are not available: Medications, respiratory rate, irregular heart rhythm notifications, ECG, AFib History, Cycle Tracking, Sleep, Wrist Temperature, Blood Oxygen, Walking Steadiness, Audiobooks, Remote, News, Shortcuts, and the double tap gesture.