I would advise against walking, since the road is sometimes steep and there is no pavement. Cars are running very fast (Austrian/German style). Certainly in wintertime, it would be a challenge to walk the 5 km. I am not aware of any shortcuts that you could take on foot.

Ciao. Ci sono le baite lungo le piste da sci. A due baite si arriva comodamente con l’ovovia Millennium. Per i negozi ti consiglio Hermagor, piccola cittadina a 5 km circa da Nassfeld.

Hi Frangisko, Reading this answer, you got to keep in mind that weather is somewhat unpredictable this far advance and climate change isn't helping much. Either way, I've been three years in a row to Nassfeld, they always start venting artificial snow early in December and by the second week of January you get several heavy snow seasons meaning you get most of the tracks open. Two years ago, I went the second week of January and there was enough snow to ski comfortably, yet it did not snow throughout my stay. Last year, I went towards the beginning of February, there was plenty of snow, yet it was heavy (wasn't the dry, fresh one you get after a heavy snow). It was enjoyable but it wasn't the softest I've had. What I am trying to say is: Unless you are a professional wanting to slide down every track, there will be snow on most tracks by the end of January (which tends to be the coldest part of the winter). Cheers!