Do you think my dog could do competitive agility or obedience even though he's shy and weary?

He's a Shetland Sheepdog. Shyness is a common trait for the breed. I didn't do anything wrong in raising him. In fact, my other Sheltie who is a bit older is the complete opposite. She is not afraid of anything nor even a bit shy. They are both very intelligent. However, she goes to obedience and agility cles but I'm afraid he's just too shy. I couldn't see him doing any of the agility obstacles. The one thing he does have going for him is that he is very food motivated and for the right treats, he might forget that he's shy for a while! How can I prepare him for a cl? Is it too late? I should've taken him to puppy kindergarten but it's way too late for that! One thing that I've noticed is that he is intimidated by large dogs but not small ones that are around his size. He does sit,down, stay, and come well at home for me. He walks on his leash but won't heel and look me in the eye. What can I do?