That's an assumption that isn't rooted in anatomy. You need nerves to measure signals on. Look up the comparative anatomy of the human cauda equina vs that of a dog. Where you're thinking of plugging into the body, in a human you'd be left with the filum terminale, which is going to sorely disappoint if you are looking for nerve signals.

To get any meaningful spinal communication in this hypothetical scenario, you'd be looking higher up in the sacral region. Unless this hypothetical also includes some magic star trek technology, you'd be invasively implanting electrodes there, which sounds like a fantastic way to trigger fecal incontinence and chronic pain.

I get the fun idea of returning humans to our primate origins, but modern human anatomy has left us effectively nothing to work with. It's an anatomical dead end.