Recently I've gotten into low-power RF technology and have become quite the fan of the nRF52 SoC for that reason. Of all the BLE-capable chips I've used so far these ones reign supreme in terms of functionality and ultra-low power consumption. One of the more interesting boards I've seen powered by them is the nRF52840 dongle , directly from Nordic Semiconductor. It's tiny, well constructed, and supports a very nice set of specs: 64 MHz Cortex-M4F 1 MB Flash 256 KB RAM 2.4 GHz Transceiver (supports Bluetooth 5 with long range) In this video I introduce the Nordic nRF SDK for programming these dongles:
(exploratory programming and more)