Check the weather, set timers and alarms, control your smart home devices, and more by speaking to a voice assistant on Fitbit Sense, Fitbit Sense 2, Fitbit Versa 2, Fitbit Versa 3, and Fitbit Versa 4.
Over the coming weeks we’ll be progressively phasing out Google Assistant on Sense and Versa 3. This means that Google Assistant voice control for activities will no longer be available on your Fitbit device. You can learn more about this process here.
You can still continue to use Amazon Alexa voice assistant on your Fitbit devices. For more information check, How do I set up a voice assistant on my Fitbit smartwatch?
Amazon Alexa is only available in certain languages and countries at this time. Check Which countries and languages are supported by Google Assistant and Alexa Built-in on Fitbit?
To learn about the Assistant experience on mobile upgrading to Gemini check The Assistant experience on mobile is upgrading to Gemini.
in the Fitbit app, tap your profile picture 
your device image.
or Timer app