I think I saw an article here that says that a few times per century, a star explodes in a distant galaxy and the resulting radiation can interact with a spinning hard drive in such a way as to allow Facebook to enhance their ad targeting profile on you. So no spinning hard drives, please.
Airgapped? That's easy; get a Windows laptop and wait for the Wi-Fi to fuck up.
That actually made me laugh out loud because I can’t get the T495s I am trying to sell to talk to my wifi at the moment.
And make sure to keep it in a sound-proof room to avoid side channel attacks.
Powered by your own generators 200 meters underground.
Nope. You just exposed yourself to compromise by seismograph. The Geologists know what you're up to.
Just delete the network firmware and forget to rewrite it.
Inside a faraday cage to prevent RAM from emitting radio waves.