My son has started comparing himself to academy players

I would not tell him academy football does not matter. He can already see that it matters to children around him. What I would change is what he uses as the comparison. Instead of “am I academy level?”, bring the conversation back to things he can control: what is improving in his game, what he enjoys doing, and what he wants to get better at next. Two children can be in completely different environments at ten and still develop in very different ways over the next few years. It also helps if adults stop using academy status as the main football compliment. Praise specific things: brave receiving, better decisions, persistence after a mistake. Ambition is fine. The problem starts when a badge becomes the scorecard for every child. He can want to improve without needing to prove he belongs in somebody else's programme.