I'm sure you know this, but trouble focusing could stem from many issues, the vast majority of which can be treated. ADHD is a big one, but there's others too, some behavioural.
If you haven't already seen one, I'd book an appointment with a psychiatrist and/or a psychologist. I wish my parents had done so when I was the student with trouble focusing so I could have received the help I desperately needed but never got, which made school miserable.
Your kid is going to have internet connected devices around him his whole life, so figuring out how to focus in spite of them is important, and there's nothing wrong with asking specialists for help.
If you haven't already seen one, I'd book an appointment with a psychiatrist and/or a psychologist. I wish my parents had done so when I was the student with trouble focusing so I could have received the help I desperately needed but never got, which made school miserable.
Your kid is going to have internet connected devices around him his whole life, so figuring out how to focus in spite of them is important, and there's nothing wrong with asking specialists for help.