I understand carriers don't want the average Joe to mess with the radio, I'd be totally ok with that, so I would agree on closed source firmware on baseband if

I understand carriers don't want the average Joe to mess with the radio, I'd be totally ok with that, so I would agree on closed source firmware on baseband if it was limited only to that use: a fully separated system that deals with connections and nothing else. All data could be en/decrypted on main device CPU, so that the radio closed firmware would essentially have full access to noise. Of course IP addresses could not be masked, but they would be available anyway to authorities with full access to cell towers and traffic.