Assange is a public figure; if extradited he will have a trial, and if convicted will go to the same federal prisons that all people convicted for federal crimes go to.
The US has engaged in "extraordinary rendition" (many of which we only know about because of Assange). I'm not defending their record here, but Assange is not a candidate for anything like that -- he is a public figure.
https://www.supremecourt.gov/opinions/21pdf/20-827_i426.pdf
"On appeal, the Ninth Circuit agreed with the District Court that much of the information sought by Zubaydah was protected from disclosure by the state secrets privilege, but the panel majority concluded that the District Court had erred when it dismissed the case. It believed that the state secrets privilege did not apply to publicly known information.
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Here, the information held by the Ninth Circuit to be nonprivileged would necessarily tend to confirm (or deny) that the CIA maintained a detention site in Poland. The Government has shown that such information — even if already made public through unofficial sources — could significantly harm national security.
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Here, the state secrets privilege applies to the existence (or non- existence) of a CIA facility in Poland, and therefore precludes further discovery into all three categories of information the Ninth Circuit concluded to be nonprivileged.
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This case is remanded with instructions to dismiss Zubaydah’s current application for discovery under §1782. P. 18. "