Seems to be a fork of Nunu with extra bits for scanning stuff.

https://github.com/Robby69400/UV-K5-Firmware-Robby69

Online flashing website here -

https://egzumer.github.io/uvtools/?firmwareURL=https://github.com/Robby69400/UV-K5-Firmware-Robby69/releases/download/V5/Robzyl.V5.FR.bin