Someone had an issue with BillboardGuis not receiving input events recently, and it was caused by the Active property being false. I’m guessing that the Active property might control if gamepads can select its contents to. Have you tried turning the Active property to true for the BillboardGui and its descendants?
It does work with PS4 and Xbox gamepads. Im guessing you’re trying to selected the button with A but you actually need to have the little dot in the middle of the camera positioned over the button and press the right or left trigger (I forget which one) and it will act as a click detection(99% sure it will be sensed as a click). I know this because Sonic Onset Adventure used a text button to tp the player to their test level and it worked.