I recommend against plugging red light into the wall if it’s designed to accept a power bank. AC power induces harmful EMFs. DC power does not, unless there are fans or pulsing. So a wrap with a power bank is just about the best way.
Thank you, I agree with you. I’ve decided to also order the one your wife use, it will be delivered on Monday. I’m going to use the bigger one for my back and the smaller one on my wrist
@Cat is correct: Batteries are by far the cleanest (least EMI) source of electrical power you can get. I am not saying it is zero, and there may be a bit from the voltage-level conversion in any given power bank (any battery voltage needs to be up-converted or down-converted to meet the USB 5.0 Volt standard), but in general batteries will always be much less than the EMI you get from other sources of power.
I am not just saying this because I read it somewhere; I have measured it in detail, many times, for the past 35 years, since I also design high-precision medical and scientific research devices that require ultra-clean electrical power sources.