Thanks for your honest feedback! If I were ever to change the data-source, I would rely on users uploading TCX files. But for now only Strava is supported, hence the name ;).
I feel like the existing self-hosted alternatives to Strava are really mature already. So I'm not sure if adding another one would be smart? Might be wrong though
This is not ment to be an alternative to Strava, but an addition to Strava. For an alternative I suggest you checkout https://github.com/endurain-project/endurain