In reply to AntonSC:
Sounds like you want the GPS as a psychological crutch. The following is far more important ;
being properly hill fit (lots of 12+ hour multiple munro hill days), and being happy pushing hard uphill.
Getting your nutrition and hydration on the go sorted.
Being good at climbing in your chosen ridge foot-wear. Ideally up to VS. Also having days just soloing diffs and Severes on your local crags under your belt.
not carrying too much shit, if you are ready you won’t be taking more than four slings and half a dozen nuts max.
A little bit of route finding nous…
…then in good weather you won’t need the gps, the only benefit of GPS is in positively identifying the cols for escape routes in very low viz, as all the other posters have said it’s wouldn’t be useful for the actual scrambling. You can plug those GRs in yourself.
If having got all the above sorted, you won’t need more than the briefest of route descriptions. If you feel the need of a guidebook, a gps track and/or a guide your not ready.
Yours pre detailed guidebooks, pre haveys map, pre mobile, pre gps and pre guide / instructor commercialisation.