I did it at that age. And not from new locale to home... well, sort of. My parents actually moved while I was in college. This was in the days before cell phones (the big bag car phones were around, but it was unheard of for a college student to have such a device). Mine dad actually mailed me a handwritten page with the directions to get there (names of hwys, approx miles before the next turn, etc... it was a LONG way on I-95 north bound and I-26 --from Florida to the mountains in northwestern South Carolina). I bought mine own car atlas/map, and had to navigate for myself without a travel mate, or any sort of tech to tell me turn by turn.
It was fine. And I'd never been to their city before. Let alone their new house. At least when your daughter gets to the tail end of her trip she'll be in familiar territory.
And I have no doubts she has both a cell phone for emergency calling if needed, and navigational apps with turn by turn navigation as well.
Maybe she'll have a friend come with her for this. You never know.
Try not to worry. I think riding TO PA with her for the first time is not a bad idea. She will be unfamiliar with her destination, and if there are any snafus, it will be good to have you on hand to help out (she will be tired after 8 hours and if anything go awry, she'll be unsure where to turn--literally). Worst case, if you are with her on the trip out, if she has a problem you can rent a hotel room to face the issue the following day. But once she's there, I think she'll get her footing quickly and the return trip to home will be no big deal.