Messi is a talent no doubt about that! He's been fortunate to have such a lengthy career too. He's looked after himself well.
I'm sure your grandson will find his own way. I think one of the worse things that can happen to a sportsman or sportswoman is that they lose the love for their chosen discipline. If he loves what he's doing, he won't need any guidance. He'll just need a taxi

to get him to practise and matches. We know a young lad whose parents take him an hour down the road and back throughout the week to play for Crewe youth setup - one of the better known youth academies over here. Half of these kids wouldn't get anywhere without the simple stuff like driving them around and washing their kit.
You sound like his go to chauffeur and cheerleader