I use YAC Reader to read comics on the big screen in the living room connected to the PC, and so I'd like to use gamepad for a more convenient use than keyboard/mouse.

For now I mapped YAC key shortcuts with the software Joy2Key. This allows full reading control by gamepad, as well as navigating a bit through the library, which is very practical and pleasant to use in my case.

Native gamepad support in YAC Reader / YAC Library would be a great feature. Is this something that has been planned?

I didn’t think about it to be honest. I will consider it if more people get interested.

Of course, and it also depends on the devices/systems you want to port the software to.
As long as the PC version works as it does on Windows it suits me anyway for my use case.