>Chips that allow you to pay for stuff by waving your hand at a sensor

You've been able to do that relatively cheaply for at least a decade. Nobody really does because the market for even minor surgeries that can essentially be replaced by having a pocket is pretty small.

Implanted neural interfaces have a lot of technical challenges that I think make them extremely unlikely as purely elective procedures in anything like the immediate future. AR glasses are way more plausible.