A second (or fraction of a second, depending on how long it takes for the magnetron to get up to full power) in a microwave works wonders on radios that can't be disabled or removed.
You don't want to give it any longer than that though because it might cause physical evidence of damage (arcing on PCBs, ICs with holes in them, etc.).
Yes, but that may not matter if the total duration is kept very low.
Many IoT-type radios use the same 2.4Ghz band as domestic microwaves and will be destroyed in a fraction of a second as the radio's AFE (analogue front end) is hit by many many orders of magnitude more energy than they're designed to tolerate.
I would wager that many devices that don't have other significant "energy-catching" features (antennas, radios, coils for NFC, etc.) would work just fine after experiencing a short stint in a microwave.
I did actually test this once on a very old 3G modem/radio interface and I found that every part of the interface seemed to function just fine, except that it could no longer receive any radio signals (and may have been unable to transmit but I couldn't confirm this with a spectrum analyser). The modem otherwise operated just fine and would talk to the SIM, operate all its LEDs and even seemed to pass an internal self-test feature that it had, with the obvious exception that it could no longer find any radio towers.
I obviously can't guarantee that your stuff won't blow up, so don't come blaming me when your device ends up being trashed by microwave energy going through unintended parts.
You don't want to give it any longer than that though because it might cause physical evidence of damage (arcing on PCBs, ICs with holes in them, etc.).
Or so I've heard.