Saw a demo somewhere, so they must exist :) But yeah, won't work with two devices with simple PCB antenna. And possibly multiple receivers to achieve the advertised centimeter accuracy...
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Yes, nRF52833 works, albeit with a few hacks. Until a tweak by @fanoush recently only 64k RAM was used.
I'm not sure I understand. BLE Signal direction finding only works when used with a high-end multi-aerial gateway. I'm not sure they even exist yet