“This is just a fun project, it was started to pass the time, it is not at all professional.”
Someone built an open-source Flipper Zero clone out of an STM32 microcontroller, some RF modules, a PN532 NFC reader, and an OLED screen, all programmable through Arduino IDE. It does RubberDucky HID attacks, IR capture and emulation, RF signal work, and RFID/NFC reading. The project has 1,600 stars on GitHub, which means plenty of people want a cheap alternative to the $170 Flipper Zero. GPL-3 licensed, which means unlike the real Flipper Zero, nobody can lock this one down.