As if mind-to-thumb-to-button is a limitation needing to be overcome…
There are interesting avenues to pursue with electronic shifting; a direct brain link is not one of them.
Automatically selecting the most appropriate gear is achievable and might be especially valuable to full suspension bikes with drivetrain/suspension interactions, but you still need buttons for manual overrides and to avoid automatic shifting at the wrong moments. This brain sensing stuff and full automation is the exact wrong direction to be going. Riders need the bike to do the right thing MORE often, not less. I think logging gear selection along with other data might be useful for training. Add grade, speed, cadence, and power sensors instead of brain sensors and you’d be in business. They aimed for Prius but made a Pacer.