Fitbit's OS for the Sense and Versa 3 won't come to earlier smartwatches | Engadget
Fitbit OS 4.1 brings smart wake to older smartwatches, better heart-rate measuring for Versa 2
Amazon.com: Fitbit Versa 2 Health and Fitness Smartwatch with Heart Rate, Music, Alexa Built-In, Sleep and Swim Tracking, Stone/Mist Grey, One Size (S and L Bands Included) : Electronics