I'm looking to create a cheap air-gaped computing device to store and utilize sensitive data like cryptocurrency wallet addresses or PGP keys. Now, I'm a total newb when it comes to Raspberry Pi but they do seem suitable for these applications, save for the fact that most Pi boards have Wifi and Bluetooth built-in, which is actually undesirable in this case. The original Pi Zero doesn't have Wifi and Bluetooth built-in, but it's difficult to obtain from where I live, and it only has a single MicroUSB port for input, so a standard model might be preferable.
So my question is if and how I would be able to physically modify the board in order to disable wireless networking functionalities on a Pi Zero W or Pi 3? Alternatively, might it be feasible to simply shield the board or (ideally) the wireless components using a faraday bag or similar?