Adafruit Feather nRF52
Adafruit has enriched the Feather line of boards with interesting newcomers based on the Nordic nRF52 MCUs.
The Feather nRF52 boards feature Bluetooth (BLE) with the Nordic nRF52832 and the Nordic nRF52840.
The Nordic nRF52832 provides 512KB flash and 64KB SRAM, while the Nordic nRF52840 offers 1MB flash and 256KB SRAM.
Adafruit offers multiple options, up to three, to upload the executable to the boards.
As always, Adafruit provides the libraries for BLE and excellent documentation for each board, with the Bluefruit nRF52 Feather Learning Guide and the tutorial Introducing the Adafruit nRF52840 Feather.
The Bluefruit LE Connect app is available for Android and iOS smartphones and macOS, and interacts with some of the examples, like serial over BLE and colour picker.
I managed to upload and debug with the Segger J-Link.
Both command-line J-Link and GUI-based Ozone detailed at the Segger J-Link Software page can be used to debug against the Adafruit Feather nRF52 boards.
Soldering the SWD 2x5 1.27 mm connector on the Feather nRF52832 wasn't difficult and is detailed at Segger J-Link with Adafruit Feather nRF52832.