When your chain comes off on the right side of the big ring, all you have to do is keep pedaling lightly and shift the rear DR to one of your lower gears. There is, or usually is a post between the crank arm and ring that not only keeps the chain from getting wedged between the crank, but also holds up the chain so it can re-engage the cogs at a certain point in the rotation.

I've done this a fair amount of times over the years and it usually works except for times when you are having to put a lot of power into the pedals due to terrain and such.

On bikes with friction shifters, I might even move the front DR slightly left, but with indexed shifting, I wouldn't try that.

I'm not a fan of gizmos that are added as remedies.