I believe Lumen to be working in 5.0.3. Nanite isn’t showing up. Instead I get a low rez geo when I set the viewport to wireframe. In 5.1, both Lumen and Nanite don’t seem to be available. As a test, I’ve added an omni light and must bake it every time it is moved unlike in 5.0.3 where it updates by itself. Instead when a light is modified in 5.1 the bounce disappears and there’s the words “preview” until it’s built again.
I still follow tutorials as though I had Nanite working for the sake of learning. I’m hoping Mac user’s patience are rewarded eventually and can get Nanite and Lumen “out of the box” and not have to fiddle with alternative builds.