I don’t tell my son he has to find a passion. I tell him to find something on which he can spend at least 40 hours per week for many years and still not hate it.
Oh you hit on a pet peeve of mine. I hate the word “passion”. I think the expectation that people “find their passion” sets unrealistic expectations, and people end up feeling like something is wrong with them or they made a wrong turn somewhere because they aren’t living this Grand, Passionate Life.
A good percentage of jobs just aren’t that interesting, and it’s ok to work on one of those jobs if it provides something else you need, like good pay, flexibility, stability, a pathway to a better job etc.
I think life isn’t about finding your grand passion, but trying to find happiness in every day things, like the specific color of green the first few days of Spring, or your friend’s smile, etc.
So sorry OP to go off about my pet peeve. Regarding your son, I wouldn’t worry about a lack of passion but instead look to see whether he’s engaged and whether there’s anything in his life that he derives pleasure from.