Yip making an interface for HAI HIfi multi-room audio controller, it is an 8 zone (room), 6 source controller. We also have a 4x4 HDMI matrix switch that has a serial port so eventually the software would ideally be universally. But I am just taking baby steps. This is just a hobby for me, for my own satisfaction.

There is lots of hardware out there that control lights and automation etc that you could write software for.