Fitbit is releasing Fitbit OS 5.1 for the Sense and Versa 3, with a focus on improving health-tracking and improving voice assistance. The most important innovation is the ability to now take pulse oximetry readings when you're sleeping without the use of a dedicated clock face. That said, the company will also launch seven new SpO2 clock faces to the platform between now and the end of the year. In addition, users can now switch between Google Assistant and Amazon Alexa by choosing which option you'd prefer inside the companion app. And while Google wants to welcome Fitbit under its umbrella, the company isn't neglecting Alexa integrations on the platform, with OS 5.1 offering spoken responses to commands.