Yes it is indeed softer and finer in it's characteristics and I too have seen it harvested using FUE.
But again the real critical issue with nap hair is "how permanent is that hair" in contrast with terminal hair from the scalp region. That's the challenge in the decision for any patient trying to make because there is a lack of clinical data. The clinical trials would show the exact location of extraction sites, then further documentation of yield, duration of growth cycles, length of growth within defined time intervals, etc. If anything the data could help distinguish those follicules between scalp and body regions considering the differences in their respective growth cycles.