Absolutely, but there are a few problems with this. First, I live in the US. Americans do NOT know how to negotiate a roundabout. There is a roundabout near my house. The instructions of how to use it are posted on signs as you approach. They are wrong. They actually have inside lanes exiting across the outside lanes that can continue around. So not only is it wrong but it's teaching the locals here what NOT to do at a normal roundabout.
Second, they don't fit at existing intersections.
Third, I think they would be more expensive than just a piece of tech attached to traffic lights that already exist.
I mean the best solution would be some good public transportation, but I'm trying to be more realistic here. That's for more civilized nations. In the US the car rules. And the bigger, the better.
It's funny because what you describe is way BETTER than I would have expected. LOL.