Fitbit Product Experts Alumni are retired members of the Fitbit Product Expert Program. Learn more
Welcome to the forums!
No there is no way unless you add the steps Manually. They use different Syncing programs.
Manually enter steps do not go towards Challenges or Badges
Wendy | CA | Moto G6 Android
Want to discuss ways to increase your activity? Visit the Lifestyle Forum
Fitbit Product Experts Alumni are retired members of the Fitbit Product Expert Program. Learn more
As @WendyB said, there's no direct way, but some have been able to sync the two by using Strava in between. So Garmin syncs to Strava and so does Fitbit. It does look like some extra work to set up, but if you're interested, here's a thread with more details.