Google Takeout has recently added support for exporting Google Fit data. You’ll be able to download some CSV and TCX files that include your activities and daly aggregations.
* TCX (Training Center XML) is a common file format for fitness activity data that can be imported to many fitness tracking tools such as Garmin Connect and Strava. By default, Fit samples location data with low accuracy and frequency to reduce device battery consumption. These Activities are exported into the Low Accuracy folder. Activities recorded with Fit’s active mode will contain more detailed location paths and more accurate data.
* CSV files are easily read by spreadsheet software or parsed programmatically but may not be easy to import into fitness tracking software.