Bouffalo Labs BL602 is a low-cost, low-power RISC-V microcontroller that offers 2.4 GHz WiFi and Bluetooth 5.0 LE connectivity for IoT projects for about the price of ESP8266. We first discovered it last year, together with a development board.
Pine64 created its own PineCone board fitted with the $2 PineNut module, and some reverse-engineering work has started on BL602 SDK. But there’s now another smaller BL602 module with “Machine Intelligence” (that’s the company name) BL-63B that sells for $1.5 on Taobao in China, as well as on LCSC Electronics albeit you’d need to purchase 1000 pieces to get that price, and single-unit pricing is currently $2.5.