pyusb VS RaspberryPi-Joystick

You can write python code that reads the data the scanner is sending, but it's not super simple getting up to speed on this. It might be best to search on python read usb hid device and start experimenting. The links found on the search lead to pyusb which has a tutorial. The first stumbling block is that the tutorial requires data about the device, such as idVendor and idProduct. You can write python code to find these values for your scanner if you don't know them, but you'll have to search on that.

Also, controllers that are usually used for USB on the desktop computer side are not capable to emulate USB devices, but there are specialized devices for that (random web search results - https://www.hagstromelectronics.com/usbtousb-shp.html, http://goodfet.sourceforge.net/hardware/facedancer20/, I would also dig into Raspberry Pi with USB OTG + software https://raspberrypi.stackexchange.com/questions/82850/use-raspberry-pi-as-keyboard-mouse-output-to-control-server since it's cheap and easily available, there are probably better options). There are exceptions - e.g., Raspberry Pi Zero is also a "computer" but USB OTG capable https://github.com/milador/RaspberryPi-Joystick https://unix.stackexchange.com/a/283147.