Do you know of any media that has a positive portrayal of someone schizophrenic/with psychosis?

Unfortunately, I am unaware of one. I feel it's up to us as humans to break the chains of mental illness awareness ourselves. Media often paints the wrong pictures that clutter the truth.

The movie A Beautiful Mind, sort of. He surely suffered with his psychosis, but it was part of his brilliance.

There was a comic book hero who had schizophrenia and his different personalities would manifest at times to help him solve mysteries and stuff.

Very good question.

There was a show called Black Box last year that I liked about a bipolar doctor. It was really good but got cancelled after the first season.

No.