I’m a sighted person and I’m not going to pretend I know what the right technology for any particular blind person is, but computer braille really is fascinating.
Edit: I’m not a hardware guy, but it feels like an 80x24 or larger computer braille display is well within the capabilities of today’s hardware hackers. Imagine a reverse mechanical keyswitch with 8 dots that can be put on a PCB of arbitrary size in whatever configuration to understand what I have in mind. There’s probably not much money to be made, but someone with a passion and existing financial success could really make a difference.