I would like to be able to (easily) monitor my heartrate treshold number over time/periods (selectable).

Just wondering if this has been considered any further - seems like a simple addition to make?

It could be nice to be able to create anchors in the calendar where you anticipate an athletes FTP will change throughout the season. For example, if you know a cyclist has an FTP of 350w in November, and anticipate from past data that it will be 380w in the peak of their season in May or July, being able to map that out ahead of time and having workouts track with that in real time could be great. This would be appealing compared to going in every month and manually adjusting from 350 to 355 to 360 etc. every 4-5 weeks.

Having a chart added to the library which shows what your FTP was at different points in time would be helpful in

a) tracking changes in FTP
b) making sure it is set correctly during different periods, since it will have an impact on the PMC, TSS and other metrics.