Red dot sight would be for the shotgun mainly. Mounted on top of the scope. Or the 7mm combination barrel if no scope used.

They certainly aren't useful for longer range shooting. A 3.5 MOA dot at 200 yards would be 7 inches so perhaps acceptable for a medium rifle.

The Trijicon scope looks useful and affordable for both purposes. The big red circle might be very useful for 1x two eyes open shotgun shooting as well. The lower price is suspect though. Why two or three times or more for other scope brands? Perhaps a big difference in quality associated with the price?