import all steps from fitbit

At the start of the year, I signed up for a challenge to walk a total of 2021 km (about 3.3 million steps). I keep track of this with my Fitbit Sense smartwatch and the Fitbit app. I switched to a Withings Scanwatch and would like to import my walking history into the Health Mate app. I read somewhere that this is possible, but only in the last 70 days. Who knows how I can import all of 2021? Is there a third party app that does the trick?