USBJoy2.0 - adapter. Connect your Atari Amiga C64 joystick to PC! Develop your own usb device! - Polish electronics for 3D printers, CNC, robotics, retro computers
Connect USB Joystick to Commodore C64 - Hackster.io
UPDATE] Converting the “Competition Pro Extra USB” to C64/Amiga/Atari DB9 – pagetable.com
C64 Joystick Adapter - Share Project - PCBWay
Best Amiga Atari ST C64/C128 Commodore Mouse Gamepad Joystick USB adapter TOM+ | eBay
C64 Mini Maxi Joystick Commodore Adapter Atari A PC With USB 64 128 THEC64 | eBay