Probably? Transparent -- ITO on glass is the usual answer. You can deposit the ITO in patterns rather than as a continuous layer; and a conductive layer works as a faraday cage as long as the gaps are significantly smaller than the relevant wavelength (so ~mm for mmWave). So a ~500 µm grid could be laid down on glass in front of the screen, and conductively joined to a continuously conductive layer surrounding the back of the phone. The question, then, is whether the change in capacitance from a finger is observable by the touch screen through such a mesh... my intuition is that it would be, but would have to either model it or test it to find out. (Could test with just a stainless steel mesh from the hardware store.)

But none of this helps with the "toggle-able" part of the requirements…

> chip bag Italian meta data incident

I’m not familiar with this one and search didn’t get me anything that seemed relevant. Got a link to something describing the incident?

What is the chip bag Italian meta data incident?

What is the infamous chip bag Italian meta data incident? I have had a quick search but nothing obvious jumped out. I'm very curious!

No; if a phone has both a non-removable battery and a baseband modem, then various laws require that modem to be wired directly to that battery (and to the phone's microphone) and to able to be activated in response to a legal wiretap order, even when the phone itself is nominally "powered off."

(And this doesn't even require that the phone stay connected to the network after the wiretap-enable packet is received. Rather, while the phone is "powered off", the baseband modem might sit there passively acting as a bug, capturing conversation through the microphone onto a bit of NAND onboard the modem; and then, once the phone is powered on again, the baseband modem will take the opportunity to silently play back whatever it's recorded to the tower.)

> if your use case is that sensitive even carrying a smartphone seems questionable.

The issue is that, if you're an actual honest-to-god spy (or investigative journalist...) trying to poke their nose into the goings-on of some government, then you want to draw as little suspicion to yourself as possible; and it's much more suspicious to be going around without the subject government's favorite citizen-surveillance tool on your person. In fact, to blend in, you need to be constantly using your state-surveillance-device to communicate with (decoy) friends and coworkers, doom-scroll, etc.

This is why spies are fans of the few remaining Android phone brands that offer designs with removable batteries. When meeting with a contact, they'll still slip their could-be-bugged-phone into a faraday bag, to cut off its network connectivity; but they'll also remove the phone's battery before putting the phone into the faraday bag, to inhibit this class of "powered-off" record-to-NAND-style baseband wiretap attacks.

(Of course, these are just ways to secure a phone you own + can determine wasn't subject to a supply-chain attack. If two people are meeting who aren't within the same security envelope, then either of them might be trying to surreptitiously record the conversation, and so their phones (or anything else on them) might contain a tiny bug with its own power source, that would stay active even if the macro-scale device's battery was removed. For such meetings, you therefore want to leave all electronic devices in a soundproof safe, in another room. Which will also implicitly act as a faraday cage.)

The iPhone antennagate story would suggest that sometimes this isn’t the situation.

Certainty?

In theory, an APT-type implant could keep transmitting even when airplane mode is engaged. This is what Faraday enclosures purportedly defeat.

The question was hard for me to parse; I want to carry with me a snitch, but remove its ability to snitch, but be able to restore it's ability to snitch?

My approach is; how do avoid the snitch? I just leave my phone in the car or at home.