The accuracy is going to be the real make or break for this. In a paper from 2018 they reported 92% word accuracy [1]. That's a lifetime ago for ML but they were also using five facial electrodes where now it looks confined to around the ears. If the accuracy was great today they would report it. In actual use I can see even 99% being pretty annoying and 95% being almost unusable (for people who can speak normally).

[1] https://www.media.mit.edu/publications/alterego-IUI/

Why do you say that? I often vocalize near giberrish and the LLM fixes it for me and mostly gets what I meant.

Whisper-level transcription accuracy should be sufficient