Apple Fitness + and Apple Watch Series 2

The answer appears to be no. From:

Get Apple Fitness+ - Apple Support

Here's what you need

• Make sure that you have an Apple Watch Series 3 or later and an iPhone, iPad, or Apple TV that's compatible with Apple Fitness+.
• Have your Apple ID and password ready. And make sure that two-factor authentication is set up for your Apple ID.

Apple Fitness+ compatibility.

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 with

tvOS 14.3 or later.