I really appreciate your work and love intervals.icu. The uncertain Strava API future is one of the reasons why I never made a connection from Zwifthub to Strava for automated tracking…
Manual file upload, whilst more work for the user, sounds like a good alternative to me. Garmin Connect is not really something I consider instead. I mean it will work for the moment but who knows what the future will bring for Garmin Connect.
In the bigger picture, I don’t understand why Strava is not integrating intervals.icu or is copying the metrics / ride evaluations. Those would be functions a lot of users would be happy to pay for and get a premium account.