I’m in the same boat - TrainingPeaks has data going back to ~2011. But it is amazing to me how little additional functionality TrainingPeaks has added over the years. For example, it doesn’t integrate to Garmin health / wellness, the charts haven’t really progressed - look at what intervals.icu has done. Why doesn’t TrainingPeaks have this functionality?
Plus, at least for me, the TrainingPeaks integration to Apple Health just doesn’t really work / produces duplicates.