For those who don’t understand why Neuman cannot pop Homelander’s head, Gen V explains her powers better.
Neuman actually doesn’t pop body parts as a main effect, but as a side one. Her superpowers are about manipulating blood. She concentrates blood pressure in the area she wants exploded. Supes are injected by compound V, but the latter doesn’t merge with their blood cells, it simply runs along with it. Thats why Neuman’s daughter was born human, and that’s why she can pop human and supe alike.