The Garmin watch has a multisport mode that allows recording an entire triathlon. You can add Stryd Zones to the data screen of the multisport mode on your Garmin to have Stryd power on your watch during the running segment.
The FIT file includes your swim and run, and while it will be imported automatically into the Stryd ecosystem, your data will not just be the run portion. There are three options to upload your data:
1. Set up a secondary Stryd account to avoid duplication of your data as your Stryd pod can hold up to 40 hours of running data. Then, Upload the Stryd data with the Stryd app on your phone.
2. Crop the FIT file, selecting just the running portion of your event.
3. During the triathlon, do not use multisport mode but stop the watch, and record the run portion as a regular run.