These are also wet electrodes meaning you need to apply gel to every single one. You’ll notice that the person wearing it is also not blinking or using any facial muscles, as that activity would completely throw off the very weak brain signals.

Sounds like they'd benefit from being in a sensory deprivation pool to enhance the quality of the signal!

https://i.stack.imgur.com/0Rtya.png

For now. Modern antennas are amazing. Maybe you could beamform from a lower number of devices.