This doesn’t have Wifi compatibility or the cost of an ESP8266. However, I ran across this when I found out there was support in the 2011 version of 802.15.4 for ranging. This is a UWB (3.5 to 6.5GHz) transciever operating at up to 6.8mbps with a multi gigahertz ring oscillator in it. If you sync the clocks between multiple stationary radios or use the more time consuming two way ranging methodology, you can put together a 10cm (claimed) accurate position tracker. This the first one I’ve seen available at Digikey.
http://www.decawave.com/products/dwm1000-module