I'd say, living space less important, a few hours of excercise is more important each day, and activities. Shepherd's are still at the end of the day a working dog breed, and you need to provide that for them. After that, they are probarly happy to sleep where-ever. A GS that isn't allowed out for hours every day is probarly going to find other ways to release it's energy, hopefully just your furniture, worse, cables and electronics.
(Though I have had one that was a lazy fuck, so, ymmw. Every doggo has it's own temperament too). Also, depending on nation, be sure to get a certified one, they have alot of hip issues all over the globe, almost a ruined breed nowadays in some places.