My nephew had a stroke and while in the hospital he had two more strokes his sisters and brothers gave up their rights since he was here. in new York with me the decision making was past down to me, now the hospital want to send him 100 miles away from the family to a nursing home instead of one here in town, he can't talk or see now, but that's another story can they send him away without the family consent. Also
A friend of mine is also blind and there's specific software for devices to help blind people, some of them being audio where you can speak and it converts audio to text. Look into your App store for your device and investigate all of the apps and you'll see there's plenty of software for the blind. Not all of them are free though, so be prepared to pay for some of them if you decide to get them
Not an easy task and it does involve paperwork and some court time.
You would then have more say in his placement as well as other details that involve him.
Absent an existing document or successor agent provisions, the question is not whether your nephew can speak or write but, rather, does he have the capacity to make decisions regarding his personal matters both health care related and otherwise. If he can understand what is presented to him (by whatever means) and can communicate that fact (by whatever means) then it can be determined that he has the capacity to grant Power of Attorney to another. It is not necessary for him to sign his name; as long as he can make his mark, and it is witnessed and notarized in accordance with his state's requirements the POA will be valid.
Otherwise, the only option is to obtain guardianship.
Clearly, you have no idea how the brain or nervous system works. When a part of the brain is deprived of oxygen for a period of time, whether due to a clot or a bleed, that part of the brain dies & is no longer functional. This is called a "hypoxic" or "anoxic" brain infarct. The area of the brain that was deprived of oxygen & the size of that area that has sustained the infarct is what determines the amount of damage & residual effects of the stroke. Some people have strokes where there is minimal damage because the clot was small & only a small part of the brain was affected. Other people have massive brain damage that puts them on a ventilator & unable to move at all. Other people lose their vision or part of their visual field. Other people do not lose the ability to move their limbs, but suffer from aphasia---the inability to communicate verbally. The damage done to the brain in this manner is totally different than a child born without the ability to see.
There are many others causes of paralysis---ALS, transverse myelitis, polyneuropathies, other autoimmune disorders. The cause of the paralysis is very important. There is no cure for ALS or any of its "sister" disorders, nor for transverse myelitis or polyneuropathies or other autoimmune disorders.
It is rather impossible for someone that is blind to surf for apps on their cell phone, by the way.
Many paraplegics and quadriplegics have permanent damage to their spinal cord---the amount of motor function is determined by the level in the spine that the damage occurred. If the spinal cord is severed or damaged to the point that it cannot be repaired, very little can be done to change that, and no amount of "technology" is going to repair a severed or irreversible spinal cord injury. If a person loses a limb, prosthetics are often used for their mobility. Assuming that "technology" can make every paraplegic & quadriplegic walk again is rather absurd. Furthermore, this "technology" you speak of costs hundreds of thousands, if not millions, of dollars.
Your post about an app converting audio to text is rather ridiculous----the OP's nephew is blind. He can't read text.
You were adamant about speech therapy---the OP said he is unable to talk.
Making a comment about disabled individuals having "no excuse" for not living a normal life is an ignorant one. Even if you remain blind & depend on audio assistance to live, you're still blind----you will never be able to drive a car or do other things that sight requires. That is NOT living a "normal" life.
"Special technology" for quadriplegics & paraplegics to "move on their own" does not mean that the spinal cord is healed or other nerve issues are resolved----technology that helps them "move on their own" include things like exoskeletons (which cost about $65,000), which are made of metal & do not enable normal range of motion do not enable a person to "live a normal life". Also, quadriplegics sometimes require a ventilator to breathe on their own. Assuming that these people "can live normal lives" is short sighted, callous & ignorant. Granted, there is much more that is available today to help those with brain & spinal cord injuries and autoimmune nerve disorders---but, there is still no technology that repairs nerves that have been deprived of oxygen or repairs serious spinal cord injuries. Despite what you think, this "technology" you speak of is not "rapidly improving"---it has taken decades to develop many of these things that help the disabled. Steven Hawking is ventilator-dependent, unable to move at all, is wheelchair-bound yet retains his cognitive abilities. The only muscles he is able to move are his eyes.
They are working on voice recognition apps, btw. Reference "In Touch" programme on BBC Radio 4. And stem cell techniques - is that what I mean? I do get terms muddled in my old age - to grow transplantable spinal cord cells, there has been some success with that I believe.
Long way to go; but things have come a long way too.