You can simulate the data processing of a real neuron with 1000 digital ones, a small neural net.

I think we read too much into the complexity of biological neurons. Remember they need to do much more than compute signals. They need to self assemble, self replicate and pass through various stages of growth. They need to function for 80-100 years. Many of those neurons and synapses exist only for redundancy and other biological constraints.

A digital neuron doesn't care about its physical substrate and can be millions of times faster. They can be copied identically for no cost and cheaply fine-tuned for new tasks. Their architecture and data can evolve much faster than ours, and the physical implementation can remain the same during this process.