Reminds me of the "Lock In" sci-fi series of a future society in which a significant portion of the population gets afflicted by an illness that causes total paralysis with no loss of mental acuity
You don't even need a brain implant, just a fancy small mri-like grid on your head and about 20h of training an ai-model to let it recognise different words from brain activity.
It just takes time to get this to wor if you want to train words, it could be much much faster by just training the alphabet so that you might be able to think like you're reading your own sentences.