A HUD reduces the difference in focus distance between "looking at road" and "looking at speedometer." It matters more as you get older, because your eyes focus slower.
But it’s uncomfortable for me because it requires my eyes to refocus from distant to close and back when I glance at it, which isn’t needed with an actual mirror. So I don’t use the feature.
I found myself actually using the incidental reflection on the surface of the screen instead of the actual pixels. I can't believe this arrangement is legal.
There are ways to do stuff like this.
Though I don't feel comfortable having more Meta in my life.