But I will say that I have worked bloody hard with a student over the last three years who is now 10, who was very reading resistant. He was full of bravado, and pretended to read, but couldn't. It held him back so much, academically. (I teach in a Montessori school, public school didn't work out for him, as he was bored, frustrated, ADHD and resistant to learning).
He refused all the 'baby books', and I had to really really really work on his parents with screen time (he had such high energy, they used this a lot to keep him entertained and quiet), and I had to be really tough with him, saying he wouldn't progress with kids his age if he didn't start reading (which I hated doing, but he needed very firm boundaries putting into place, to stop him playing the fool). In the last 8 months, he has really taken off and is now reading Minecraft chapter books and writing stories.
His spelling is awful and his reading is slow, BUT he has progressed so much and is now asking to go to the library. I don't think 10 is too old, but I do think that you are definitely running out of time to catch them as it's harder to find easier material in accordance with their interests... especially as this kid was super bright, but his lack of reading meant that his body couldn't keep up with his intellect.
It was definitely the hardest case I have ever had to deal with though...