I loved lightgun games on the old systems, and I think the Sega Saturn’s Stunner was the best hardware of the lot. The obsolescence of CRTs pretty much killed the tech, but the gameplay style has made a bit of a resurgence a couple times with the advent of the Wii and VR.
There’s also the GUN4IR project that can be put together for a fraction of the cost of the Sinden. The Sinden requires a visible border around your game.