Hello Hearn Cho1.
Thanks for reaching out to Apple Support Communities. We understand that you would like to know if it is possible to share your Apple Fitness+ subscription with family members who do not own the Apple Watch, and we're happy to help. Here is an excerpt from a support article about requirements for Apple Fitness+:
"Apple Fitness+ requires Apple Watch Series 3 or later with watchOS 7.2 or later and one of the following Apple devices: iPhone 6s or later with iOS 14.3 or later, iPad with iPadOS 14.3 or later, or Apple TV 4K or Apple TV HD with tvOS 14.3 or later."
Subscribe to Apple Fitness+
Cheers!