at some point it will be common to build in a tinfoil liner on all floors, walls, doors, and ceilings. windows would have a transparent aluminium coating.
would all that be enough? unlikely. but it would cause those trying to spy a bit of grief.
“tinfoil liner”
I use cellphone Wi-Fi to access FR.
I can put the cellphone in a steel Farberware pot with the lid on and still access FR.
Putting the pot and phone in my refrigerator will block access to FR.