It should work using the ESP32 BLE Keyboard library, but as far as i remember you need to send the correct decimal values, for reference look at the following link:
https://www.arduino.cc/reference/en/language/functions/usb/keyboard/keyboardmodifiers/
i am sending the following Key codes:
int KEYCODE_F5 = 198;
int KEYCODE_F6 = 199 ;
int KEYCODE_F7 = 200;
int KEYCODE_ENTER = 224;
int KEYCODE_DPAD_UP = 218;
int KEYCODE_DPAD_DOWN = 217;
int KEYCODE_DPAD_LEFT = 216;
int KEYCODE_DPAD_RIGHT = 215;
