There is nothing stopping you from using a cloth hangar. You just need to make sure it is impedance matched and properly sanitized for subdermal use. The signal will be much worse as a cloth hangar had gauge/diameter that is several magnitudes bigger than that of a neuron. Nothing here is particularly "novel" that it cannot be trivially replicated if you have the budget of one of the FAANGs. If you have 100million in capital, you can easily find poor neuroscience and EE PhDs who will be willing to work for you for <80K a year just for the opportunity to build something like this. The reason it is difficult and out of reach for smaller companies is because small amplifiers and electronic packages that can be subdermally implanted requires significant manufacturing capital as they fall under semiconductors and biomedical devices. Once the industry settle on a design expect the price to drop dramatically as the core chips and parts become commoditized.