But what's the point of bringing a phone at this point?
Other comments mentioned valid points about tradeoffs of using an offline camera vs. a phone, with pro-phone arguments listing things like "being able to livestream and get the evidence out even if the device is damaged/destroyed" and "messaging/coordinating/comms". The anti-phone/pro-camera side also had good points, saying that those things also make it easier to track/identify you. The choice between those two options is definitely not clear-cut, and it is all about individual tradeoffs and risk assessment.
But if you are rocking something that's essentially a wearable Faraday cage that block all signals (I am just assuming it works exactly as stated, without attempting to judge its efficacy), what's the point of bringing (an essentially fully offline) phone in the first place, as opposed to bringing a camera with zero connectivity?