Burris has a modular system out, 3X (or 5X), reflex, and laser, TMPR
https://www.burrisoptics.com/sights/...-sights-series. You can mix and match.
I recently mounted a Reflex on my shotgun and am now wondering why I didn't do it sooner. The old eyes are getting tired and the reflex makes aiming much easier.
Most newer shotguns either come with a Picatinny rail or are drilled for one. I have a saddle mount on my shotgun.
The good thing about the reflex is you can shoot both eyes open. Most of my shotgun shooting is instinct shooting, I never see the front bead, both eyes open. The transition was easy for me.