Another route might also be sub-vocalization[1], like TTS for your thoughts. I recently picked up some cheap toys to get started trying to emulate the results[2].
1. https://www.nasa.gov/centers/ames/news/releases/2004/subvoca...
1. https://www.nasa.gov/centers/ames/news/releases/2004/subvoca...
[1] https://neuroscience.stanford.edu/research/funded-research/s...
Got any jumping off points?
EDIT: User `tbenst` linked their thesis above[1].
1. https://neuroscience.stanford.edu/research/funded-research/s...