It's Castaway, HP edition! Harry has to survive in a state of nature and is isolated from civilization. Maybe he has his wand and the fic is a fun adventure of him journeying through the scenario as if it were symbolic of independence and self-determination where he feels liberated by both being forced to fend for himself and only being responsible for his own being.
Maybe it's a gritty story of human versus nature where he loses his wand and has to overcome his obstacles by his wit with the only magic he can use being limited potions and whatever power he can summon up from deep within himself, and he comes out the other side changed and more confident but no one in the ordinary wizarding world can relate to the experience as they have been so dependent on conventional magic and wands that they have lost sight of their own power to self-determine and survive.
Maybe it's an emotion story where Harry has been running from his problems and is metaphorically forced to turn around and face them as he is trapped alone on a deserted island with nothing but himself for company, and its not until he faces his problems that he's able to come out the other side. There's all kinds of things you could do, and it's not really something that has been done before. Supporting characters could be present or not, Fleur is the obvious choice here, but Luna or Neville would be good as well.