Crazyradio 2 UF2 Bootloader.
This was built using the command with arm-none-eabi-gcc (Arch Repository) 12.2.0:
make BOARD=crazyradio2
Can be flashed in a Crazyradio 2 using the command:
pyocd erase --target nrf52840 --mass
pyocd flash --target nrf52840 crazyradio2_bootloader-1.0.0-bitcraze_s140_6.1.1.hex
Only the DFU button is cabled to the Crazyradio button. The second button, that allows to enter Bluetooth OTA mode is set to a non-connected pin of the nRF52840.