I might add that this is pretty much exactly what Elon Musk is asking for with his "Neural Lace" idea to merge humans and machines in "symbiosis".

Replace thimble-keys with OpenBCI and you already have it.

Urbit.org sounds like a good fit for the immutable append-only content-addressable private keylog (now would be the time for a portmanteau generator). I would love to help in any way to make this happen.