The concept is interesting. Unfortunately, I've got a 16:10 screen, and I don't see my health, and just a tiny bit of the possible turrets. Though your idea is simple but very efficient. Great job.
For the Canvas, use a CanvasScaler with "Scale with screen size" UI scale mode (not "Constant pixel size"). For the sprites, a simple solution is to adapt the camera Projection/Size (orthographicSize) to fit the with of the world.
