Friendly PSA, hopefully unnecessary: If you attend one of these 'No Kings' gatherings, or any similar gathering, please coordinate with your friends/associates beforehand and leave your phone at home. Or, turn-off your phone or, at the very least, disable all the radios (airplane mode). Also, try to cover your face - Covid mask or big hat and sunglasses, and don't wear any identifying clothing, like the name of your employer. All that might sound paranoid - that's what all my friends tell me. That might be true, but I'm confident DHS also attends these gatherings to collect data. And that data is used to create named lists, the ones you don't wanna be on.

I test a lot of mobile apps, and for various testing purposes I have shielded bags for phones. It's an easy way to have an extra layer of protection because it's physical and tactile, and likely to work even if you messed up some of the other protections you should be using.