I think Von Neumann suggested what might be needed to engineer a complex self-replicating system. He didn't suggest a process that might incrementally lead to

I think Von Neumann suggested what might be needed to engineer a complex self-replicating system. He didn't suggest a process that might incrementally lead to that though (abiogenesis in the case of biological life), which might be able to rely on simple chemical behaviors to start accumulating complexity.