Adding text-to-speech to a wallet would be nice, but rather challenging to implement on a cryptocurrency like Bitcoin. Imagine the wallet speaking the private key out loud. Another person could hear it and use that same key to unlock the blind person's funds. Earphones could be used for this purpose, but I wonder how secure the whole setup will be against malicious actors. At least, the idea is there. Making it a reality is another story. Considering that blind people are the minority, developers don't feel the need to create a Bitcoin wallet suitable for these kind of people. Most blind people usually have an assistant which do all the things for them. They can simply delegate their Bitcoin to someone trustworthy enough to handle their wallet for them. This brings the middleman which crypto was meant to avoid in the first place, but it's the only way for blind people to get access to Bitcoin right now.

All in all, there may be far more important things to focus on than simply making Bitcoin accessible to people with disabilities. Once Bitcoin handles its own issues (mainly scalability), then developers might focus on bringing blind people to the crypto space. If there's enough interest into making a wallet software with accessibility features for blind people, developers will make it happen one way or another. Otherwise, blind people will be left out of the game. Let's hope everyone's priorities is put first, in order to make Bitcoin widely adopted in the mainstream world. Just my thoughts