A standard 65mm flush-mounted box is sufficient. This can be drilled into the wall relatively easily and quickly (approx. 10cm centre/centre away from the switch) and then drilled into the new hole from the switch. Of course, it is nicest if the display is mounted in alignment above the switch. But you have to pay attention to the pipe routing so that you don't drill into it (unless you change all the wires anyway, in which case this would be very welcome).
Today I installed a display at the entrance so that I can switch off all the lights in the house at the touch of a button (worthwhile if you have several sticks and children). As I said, installing it was relatively easy if you are properly equipped. If necessary, ask your electrician, he can simply let it into the wall.