> I don't feel like my focus is a problem.

He could offer many solutions to a problem with focus, headphones, flexible working hours/location, ect but not medication. He is not a doctor and knows nothing about his employee's medication history.

Manager with ADHD here. The most I'd do is suggest checking with a professional, not impersonating one with my manager hat on.

And mostly I avoid prying about mental health, except to the extent the individual relationship makes the topic come up (e.g. if they mention it).

If it's impacting work performance, I can inquire in more open ended ways than that.

It’s still not appropriate for a manager who is not acting in a medical capacity to make that kind of recommendation.

It’s a huge huge leap to go from “I feel like your focus needs improvement” to “go get an amphetamine prescription because I feel you are not working hard enough.”