Not about mental illness but a sci-fi scenario of real physical survival
A user named cetaylor3 stated quite eloquently the interpretation of the film which s/he and I share but which seems to be surprisingly rare on this board:
I think the story is readable importantly (and most simply – Occam's Razor interp) as a science fiction story of an actual (albeit mysterious) wall that is real and external to her … and which obliges her to find in herself resources of survival – physical and mental – that put us, the viewer, in the position of imagining (and being in some awe) of her strength of will to live in the face of such unimagineable surreality of existence and abandonment by and from all that is known.
Honestly, the notion that she is just another person on our regular, non-transformed world who is either not even stuck in the mountains at all, or who has exiled herself there out of choice (mental illness), is much less interesting than the actual story presented before us.
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