There is no conceivable risk to a turned off laptop, that could be fixed by a faraday bag, that is not dwarfed by having a functional networked laptop.

Technically, if it’s completely 100% off, there’s no electricity running through its circuits and CPU, then there’s no way any program of sorts can actually, physically run.

The point of a Faraday cage is to isolate what’s inside from any EM interference.

If there are no active circuits running, then there’s absolutely nothing to interfere with.

You could try running tails on your laptop. Nothing guarantees resting privacy like removable boot media

The same as a tin foil hat. Even better an Faraday Bag for your router

https://www.theregister.com/2025/07/22/whofi_wifi_identifier/