Guide to enable STDIO over bluetooth (using nimble) - RIOT-OS/RIOT GitHub Wiki

RIOT features a module called stdio_nimble which provides access to the RIOT shell via BLE. This feature is available on all devices supported by NimBLE such as the nRF52 series.

A comprehensive guide on how to set up the connection can be found in the module documentation: https://doc.riot-os.org/group__sys__stdio__nimble.html

For older Android devices, you can download the matching android app (source) which was developed specifically for this module at the Google Playstore.