Mcbazel Brook Wingman SD Converter for Xbox 360/Xbox One/Xbox Elite 1&2/PS3/PS4/Switch Pro Controller to Sega Dreamcast and Saturn Console Adpater : Amazon.co.uk: PC & Video Games
USB-GDROM for Dreamcast
USB-GDROM : てきとうにブログ
Mod Complete - Dreamcast With SD Card Slot Booting Retail Game ISOs - YouTube
raphnet. - Dreamcast controller to USB adapter (v2)