How to programmatically retrieve full activity telemetry (equivalent to raw .FIT file)?

Hi everyone,

I’m building an app that creates advanced video overlays for cycling and running. We want to use the Strava API, but the GET /activities/{id}/streams endpoint strips out advanced hardware metrics we need for our overlays.

While the basic streams (time, latlng, watts, etc.) are great, we are missing the granular data found in the original .FIT upload, specifically:

• Advanced Power: L/R balance, Pedal Smoothness, Torque Effectiveness
• Dynamics: Garmin Cycling Dynamics, Running Dynamics (GCT, Vertical Oscillation)
• Hardware: Electronic Shifting (Di2/SRAM gear ratios), Core temp, Muscle Oxygenation
• Raw GPS: Un-smoothed velocity and grade

My questions:

1. Is there an endpoint (even in beta) that allows a third-party app (with user consent) to download the original, raw .FIT file uploaded to Strava?
2. If not, are there plans to expand the Streams API to include these advanced data arrays?
3. Has anyone found a reliable programmatic workaround to retrieve this missing data while keeping Strava as the sync hub?