A paper on this was just submitted.

"We demonstrate that this class of defenses is insecure against two practical attack classes: the copy-type attack, in which a human transcribes LLM-generated text producing authentic motor signals, and timing-forgery attacks, in which automated agents sample inter-keystroke intervals from empirical human distributions."

https://arxiv.org/abs/2601.17280v1

There are tons of USB dongles available for about $10 containing a programmable microcontroller. You connect to the dongle from another device over wifi and it can act like a keyboard typing out whatever text you want using a model of human typing, perhaps even your own.