Here is a funny anecdote: Some time ago I was living in the NRQZ, where the caves are long and the EMR spectrum is empty. I was keeping my private cryptographic material on a off-the-shelf android phone with most of the antennas removed and their pins grounded, kept in airplane mode since purchase, chained to my belt. My undiagnosed neurological issues with controlling my hands had unfortunately developed already when setting that phone up, and I wasn't able to fully manage all the radios and antennas inside the device, but I figured it was still pretty helpful. Like many people used to do, I charged it with a 2-wire USB cable to make it hard to in/exfiltrate data on it. Because this phone was never online, the clock would skew badly. When I needed to use a second factor TOTP, I would have to manually set the date on it to get the right code, as it should be with TOTP. So I got pretty familiar with my clock being skewed. The people who worked the stores in this area often drove in from the edge, since product marketing is pretty heavy there and they wanted internet and such. They would take their phones into the area and use the bluetooth functionality with their vehicles or wifi tether them to illegal hotspots. At some point, my phone started turning it's bluetooth on, on its own. I don't know why this happens. It's happened to me on other devices - my present device included. When I notice, I turn it off. Phones are really used to assuming they're networked. Now, when an antenna is grounded, it can still communicate a little bit unless the radio itself is disabled. So, I was hiking to town for groceries one day because my vehicle had broken down, and one of the tellers took pity on me and offered to drive me to somebody who could tow my vehicle. Their car was set up for bluetooth with their phone. After my trip in their car, my phone's clock was synced. On its own. I didn't know a phone would sync its time over bluetooth. But now I know this can happen.