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This help article shows the compatible devices (or at least those that have been tested sufficiently to show no major issues) https://help.fitbit.com/articles/en_US/Help_article/2315
As for the Versa 2 and the S9, here are screenshots from the page:
Warren | Cincinnati, OH
Versa Lite, Ionic, Charge3, Inspire HR, Blaze(retired), Alta( retired),- Pixel 3
Take a look at the Fitbit help site for further assistance and information.
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