As a formerly insecure person, just offer to teach them if they want, and then never mention it again. Once they're ready to get over their insecurity, they will contact you, or not.

Write them a convincing argument in a letter as to why it is important to learn how to read.

I grew up very poor. In my street lived an older lady and a few doors down lived her daughter and son-in-law. The older lady was illiterate and when her first grandson was about to learn how to read, her daughter asked her to help teach him by keeping them company. So the daughter taught her toddler and her mother the bascic alphabet. That inspired the old lady to seek help and my mother arranged for a high school student to come tutor the lady three days a week. The old lady taught the next two grandkids how to read using the pamphlets she learned to read herself.

Do you know why they don't want to learn to read?

My family are the kings and queens of refusing to do things that will make thier lives better. I have learned through bitter experience that there is no helping anyone who does not want to help themselves.

Without knowing your family member there really isn’t much useful that anyone can tell you.

I recommend that you find a way to maintain whatever level of relationship you want with that person that insulates you from their “issues”.

Text to speech scanners are already available.

Get them one that lets them 'read'

mho

Are they dyslexic or have other obstacles you may not know about?

Is there a significant age gap?

Is there an app that they could use privately?