Control the Mpxplay (or any PC) Media player (even under DOS) with just a Pro Micro, Rotary Encoder and a little Nokia 5110 display (no keyboard required)...
Hackaday: https://hackaday.io/project/171821-control-dos-media-player-with-pro-micro
Basically you have a list of menu options (each of which can have sub menus) from which you select the required actions. Simply navigate to the option you want and press the button to generate the appropriate keyboard action. In theory you can generate hundreds of actions form a handful of menus.
Options: In place of the 5110 you could use a Touch Screen Displays where various graphical representations of buttons or images/icons once pressed would cause an action just like a macro keyboard. Each screen could represent a different application or more actions, it's entirely up to you...
MicroProcessor: Pro Micro IDE: Arduino
Mike