piracy is distributing copies of publicly available media.

Arguably software, films and music aren't "publically available" in the sense that they're only conditionally available to the public (ignoring piracy).

But okay, lets take the pornographic example. Say they occasionally sell nude photos to acquaintances too. Now the photos are in some sense "publicly available" in the sense that some people can buy them. Is it now suddenly okay to pirate this media? If so, then why?

accessing a private device and making copies of personal content inside is illegal and unethical.

Did you not read my very first example where I claimed almost exactly that. What have you been thinking I was talking about?