Potty training tips

My son is going to be 3 and a 1/2 and I’ve recently started to try to potty train him. I know he’s ready bc he’ll stay dry for a long time also he will pee on the potty if naked. The problem is when I put undies on him he pees and poops in them. When I ask him where he has to go when he has to potty he tells me the potty so he knows what he has to do and where he has to go he just doesn’t. I’ve tried songs, special undies, books and rewards but he has no interest in being potty trained. Someone help 😭😭😭😭😭😭