A TTL UART adapter makes it possible to connect the stick’s serial interface to a computer via a USB interface. This makes it easy to send commands on modern computers through serial emulation, just like the serial ports of the 1990s.
These adapters are widely used in the modding of SFPs, and in general of most embedded devices, since a serial port is always present in all of them and is also used to de-brick such devices.
TTL adapters can be easily found on Amazon, the most recommended one being:
Alternatively, an Arduino can be used to emulate a TTL adapter