I played Cosumi bot blindfolded on 9x9, but how about 19x19?
In my case the answer is “it’s tough”! At best I could imagine 3x3 patch of the board.
Here’s my attempt with White stones:
When I played J6 I thought H6 is further from the action, so I got confused and resigned.
I bet dans can play the game almost all the way through with some practice.
Here’s the link: https://www.cosumi.net/blindfold.html
Go play it, a rather refreshing experience. Almost like meditation in front of an empty board.