For example, the STM32F103C8T6 microcontroller has USB connectivity capability. It would be great if your library supports this microcontroller as well.
Use FreeJoy then. You need to make sure you have GENUINE BLUEPILL (not a clone) because if you don't, it will not work. It's why I went with ArduinoJoystickLibrary.
Please also provide support for STM32 chips.
For example, the STM32F103C8T6 microcontroller has USB connectivity capability. It would be great if your library supports this microcontroller as well.