Is it possible to mount a 7-Segment on an FPC and what points need to be considered?
After extensive discussions with the fabricator and receiving several different variants as protype and then after starting productin, I can answer my own question:

Yes it is possible to do
After extensive vibration testing, I can also say fatigue is no issue (at least in my application) if several key points are considered:

Do a mechanical modal analysis and make sure no Eigenfrequencies of the FPC are within the expected vibration frequencies
Add Stiffener close to the pins (and in best case around) to let the pin be mounted on the smallest possible diameter membrane

The best results out of my prototypes I had with 0.2mm FPC + 0.6mm FT4 stiffener




It is feasible for mass production (no extensive failure rate in production so far)