Run a menu board across the TVs above your counter using the TVs themselves: Samsung Frames or LG TVs need nothing plugged in.
Most digital menu board services put a small player box behind every TV and charge a monthly fee per screen. If your TVs are Samsung Frames or LG webOS TVs, they can show the menu on their own, run from a computer you already have.
Everything unlocked, any number of displays. No card needed.